Getting Started with Shapeways’ Resin 3D Prints

Note: as of July 2024 the Shapeways 3D printing service has closed down. Most of the information on this page is related to plastic processes used by Shapeways, and thus this page is mostly obsolete.

I've left it here in case it's of interest to anyone.

This page contains some tips on getting started with 3D printed products produced by Shapeways. It isn't exhaustive or authoritative by any means – it's just some advice, based on my experience, that I hope you find useful.

I'm a designer of 3D detail add-ons for model kits, via the Age of Plastic portal on Shapeways.

3D printing technology

3D prints begin with someone designing a 3D model in a computer. The model is a digital representation of the final product, and is constructed using CAD (computer-aided design) software. This software outputs a file in a standard format (eg: .STL) which is then sent to a 3D printing machine. 3D printers work by laying down hundreds or thousands of fine layers of material, slowly and methodically, until the finished three-dimensional object is complete.

There are many different 3D printing technology out there, but most machines broadly fall into one of three categories – those which use solid powder, those which use liquid resin, and those which use solid filaments.

Resin printers harden or “cure” the liquid, using UV energy from lasers or LEDs, into solid plastic. They're often called SLA (Stereolithography) printers.
Powder-based printers are often called SLS (Selective Laser Sintering) printers.
Consumer-level machines often use solid plastic filament, and are thus called FDM (Fused Deposition Modelling) printers.

In my case, I upload the .STL file to the Shapeways 3D printing company. Shapeways have a bunch of printers (and subcontracted printers) in the Netherlands and New York, and operate a salesfront web site. They're too expensive, but offer a reasonably reliable service. They also offer a ton of different printing technologies using different machine types.

Most of the products I've printed use Shapeways' Fine Detail plastic, which is liquid resin.

Overhangs – the Trouble with Resin

One of the problems with printing with liquid resin is that uncured (ie: still liquid or still slightly soft) resin can't support much weight. Only once the resin has hardened to a solid is it actually sturdy. This can be a real problem. Take the following example.

So let's say that the object in the first picture is what you want. Notice it has a piece that hangs over. Since we have to print under Earth's gravity, the sticking-out bit is going to fall off while the liquid resin is still hardening (second picture).

The usual solution is to position an array of thin sticks, or supports, to hold up the piece during printing, as in the third picture. You then have to cut the supports off once the resin is cured and cleaned. The problem is that cutting off the supports can leave little nubs that must be removed, and sometimes the process can destroy detail.

The best approach is also the most expensive. Multijet printers squirt out tiny droplets of two kinds of material - plastic resin and a special wax. The wax, shown in the fourth picture in red, is used like a scaffolding to hold up the overhang. Then, when the resin is properly hardened, the part is heated and washed to removal all residues of wax. The result is a neat plastic shape with an overhang!

It's quite an ingenious system, but the use of wax has drawbacks. Depending on how thorough cleaning was, you will probably end up with some oily waxy residue on your print, especially in enclosed areas. And any piece of plastic that contacts wax is going to be slightly rougher than plastic that doesn't.

Also, obviously the example above is contrived. If you really wanted that simple L shape you'd just print it upside-down to avoid the problem. However, complex parts with undercuts and overhangs can't always be printed upside-down like that.

Shapeways “Fine Detail Plastic”

Shapeways have used two basic generations of high-resolution liquid resin printing that they market under the name “fine detail plastic”. Both types are multijet (material jetting) resin processes, and use wax supports.

The first generation of Fine Detail, formerly marketed as "frosted plastic" uses ProJet machines. This generation is produced today under the names “Smooth Fine Detail Plastic” and “Smoothest Fine Detail Plastic”. This process is no longer available.

The second generation uses 3D Systems Visijet printers, and Shapeways offers the prints in “Tan Fine Detail Plastic” and “Clear Ultrafine Detail Plastic” detail plastic. This is the process available today.

Of all the Shapeways printing processes, the Fine Detail prints are generally the best for model-making details. All the others are intended for other applications, such as metal printing for printing jewellery.

Powder-based “ Versatile Plastic (Nylon 12)” is the cheapest option, but not very suitable for models because the prints have a coarse texture like a sugarcube. Nylon 12 is also a difficult plastic to sand. The same problems apply to HP print processes.

Before 2023: Smooth and Smoothest

Smooth Fine Detail Plastic (formerly Frosted Ultra Detail or FUD) and Smoothest Fine Detail Plastic (formerly Frosted Extreme Detail or FXD) were the first type of wax-supported prints produced by Shapeways. The technology was dropped in 2023 because the printer manufacturer had discontinued the printer, forcing Shapeways to move on.

After 2023: Tan and Clear

The second gen process, introduced in 2023, is a bit different. It actually prints wax around the entire object while printing. This means that you don't have the situation where wax-contacting surfaces are rough, and the others are smooth.

Unfortunately there are some serious issues with the tan and clear processes. I've written up a separate page on that problem.

Three points

An important issue I want to stress is that the 3D models produced using Shapeways’ “fine detail” printing process are pretty amazing in terms of the detail they can hold. But you need to keep three issues in mind: brittleness, cleaning, and print artefacts (or “artifacts” if you're in the USA).

1) Brittleness

When hardened through exposure to ultraviolet energy, Shapeways acrylic resin becomes permanently solid, but with two seemingly conflicting properties.

First, when in the form of thin sheets, the material is slightly flexible. It bends quite easily, which limits how small or thin a print can be. But if flexed slightly too far, the plastic will simply snap into two.

Second, when the material is slightly thicker it will resist bending, but will continue to be really brittle and easily broken.

Acrylic is thus quite different from the slightly flexible styrene used in most injection moulded model kits. Styrene will weaken and bend sharply, turning white at the bend point, instead of snapping immediately. You can then bend it back and forth repeatedly at the join until fatigue sets in and it finally breaks.

Acrylic's brittleness is important for a number of reasons. First, it puts limits on the kind of tools you can use. Second, it affects how much handling the models can withstand.

And, as noted, the tan and clear plastics are much more brittle than their predecessors.

2) Wax on, wax off

So the key to good preparation of these parts is cleaning. Especially if a part wasn't properly cleaned by Shapeways, and arrives still full of cloudy blobs of wax, like the Smoothest one to the right. There are different methods for removing the oily wax from the parts, some of which I've tried and some I haven't.

Summary: personally I find the best overall approach to cleaning is to use a fine-tipped medium-coarse bristle paintbrush, and gently use it with hot water. This combines the wax-melting properties of heat with the physical scrubbing motion. Put a fine sieve in the drain to avoid losing parts.

Once I'm done, I use a fine knife to smooth the surface and remove the final residue.

Hot soapy water

This works pretty well, since the wax is easily softened with heat. You don't want boiling water, which could damage the plastic and definitely can damage you. Hot water from the tap seems fine. I've run a stream of hot water over the cockpit of a spaceship model to release the wax from inside the near microscopically tiny interior, using a very thin wire to loosen the softened material as it goes. This takes time but works well.

You can use a soft bristled paintbrush or toothbrush to work in finer areas and corners, but be very very gentle – it's easy to snap off fine details inadvertently. And mind you don't lose smaller parts down the drain! That's happened to me, and it's expensive and embarrassing.

Detergent

Ordinary liquid dishwashing detergent can be added to the hot water to help release any traces of oily residue. This usually requires a light brushing while you're at it. I don't recommend soaking the parts for days, as that seems to result in the plastic becoming extra-brittle and weirdly textured. It also turns the wax into this crumbly kind of material that still sticks to the plastic.

Alcohol

Some people report that using isopropyl alcohol (IPA/isopropanol) works well as a cleaner. I wouldn't let the parts soak though. Lengthy exposure makes the plastic brittle and also opaque white in colour. It can also attack detail. Careful application of isopropanol with a brush, so you're relying on the physical brushing motion, works well for me.

Ultrasonic cleaners

Ultrasonic cleaners are steel tubs for liquid (such as plain old water), with a high-frequency noise-making device at the bottom. The ultrasonic sound travels through the liquid, and causes the formation of tiny bubbles through a process known as cavitation. This agitation of the liquid causes contaminants to work loose from the object being cleaned.

I bought one of those small ovoid-shaped plastic ultrasonic cleaners used for cleaning jewellery. It was pretty cheap, and utterly useless. It did nothing.

So I got a larger one. It's a more serious-looking metal box, and it seems to do a far more reasonable job. It has a more powerful ultrasonic output, and also contains an electric heater to warm the water. I tried with alcohol (not directly in the tank as it's a fire/explosion hazard. I used a semi-covered container of isopropyl alcohol suspended in water) and that turned the plastic a snow-white colour. The plastic also became more brittle after the alcohol/ultrasonic treatment.

Ultrasonic cleaning works as a first round, and Shapeways uses ultrasonic cleaners as part of their cleaning process. But I personally think that using a fine brush with hot water is the best way to get all traces of wax off a model. It's the physical action of the brushing, accompanied by the wax-softening hot water, that does it. I do an ultrasonic clean first, then go over it by hand.

Solvents

Much like the detail section, some people recommend various kinds of stronger solvents for cleaning, such as acetone and so on. I personally haven't experimented with any, since anything that can actually attack and weaken the plastic seems like a bad idea to me. The prints are fragile enough as it is.

But that's just my view on it. Feel free to experiment, but remember that Shapeways won't do a return or reprint on something damaged by solvents or other harsh cleaning strategies.

Knives

As noted above, areas of plastic touched by wax always are rougher. And the water or solvent cleaning process still ends up with a kind of crunchy or fluffy white residue of wax garbage. This sucks.

In the end, I actually find that the tip of a brand new knife is one of the best ways of removing the residue left by the wax, even after cleaning. You have to go extremely slowly, with a powerful magnifier, so you don't inadvertently scrape off any detail. Use the side of the knife blade tip, and gently scrape it against the surface. It's time-consuming, but worth it!

Before 2023: Translucent or milky

Smooth or Smoothest plastic that has been cleaned sometimes turns cloudier or milkier, depending on material thickness. The wax seems to make thinner areas slightly more translucent, sort of like onions fried in oil. So removing the oily wax reduces translucency.

Note: this last point doesn't apply to the new clear plastic process.

Compare these two shots. The first shot is a Smoothest part before cleaning; the second is after. Note that the second model isn't painted or anything - it has simply been cleaned with alcohol, which renders it a nearly opaque white; almost pale grey.

Sticky times

The 3D printing process used for these parts is a form of stereolithography which employs an ultraviolet (UV) laser to harden, or cure, the liquid resin. However the process isn't always perfect and you sometimes end up with slightly sticky surfaces if the resin isn't fully hardened.

If that happens you'll need to expose the plastic to some UV. In most parts of the world a few hours in direct sunlight should do it. I wouldn't take this step unless it's needed, though, as excess heat can also warp and damage the plastic.

3) Print lines

The 32 micron layers used by Shapeways Fine Detail prints sounds super high resolution, and are certainly amazing in their own right. But even this state of the art for 2024 still results in visible layers and strata. And while the blobs of plastic laid down by the jets are incredibly tiny, some details visible in the original 3D model may not be fully resolvable in the finished print.

Curved or barrel-like surfaces (e.g.: the Millennium Falcon saucer surface) result in particularly objectionable print artefacts, because the lines appear as scalloped curved steps. Flat surfaces, when printed at any angle that isn't parallel or perpendicular to the flat printing base, also show bad print lines.

I find a number of techniques work fairly well to reduce the appearance of these lines.

Sanding print lines

The obvious approach for larger flat areas is to use extremely fine emery cloth or sandpaper. Carefully applied, this reduces the ridges effectively. By increasing paper grades from fine to ultrafine (e.g.: finishing with four-digit papers like 1000) you can get a polished look. The big problem is that it's easy to sand details away as well.

Filing print lines

As mentioned above, I find high quality needle files to be essential. The ones I end up using most are flat rectangular files for precisely reducing flat surfaces and removing print lines. And curved files for opening out circular holes. It's slow going, and it's good to have a few grades of files from fine to ultra fine, but they're useful and necessary tools. The expensive files tend to clog up with acrylic dust a bit less quickly, but you do have to wipe them clean continuously as you go.

Scraping print lines

Another approach is to gently scrape the ridges with a very sharp blade (eg: X-Acto 11 or 16), holding the cutting edge nearly perpendicular to the surface, but leaning it opposite to the direction of travel. This can give you very precise control, but takes forever for larger items. You also need to be totally in control, as a slipped blade can easily slice off detail. Or, it needs to be said, your finger!

This technique is one way of reducing print lines which appear on curved surfaces, assuming there aren't also a bunch of fine details there.

I actually recommend this approach for getting rid of a lot of print lines.

Filling print lines with putty

Another tack, though one I generally dislike, is to use filler. Sometimes I use new tubes of Tamiya putty when it's still slightly liquid, and apply it with the tip of a knife blade. Then, while it's still slightly soft, I carefully cut the putty back, leaving it in the trenches between ridges. Then I scrape and sand carefully once the material is completely dry. This is another technique that requires tremendous care and precision, as you can easily destroy details this way.

Solvents and print lines

Some people advocate solvents, often in vapour form. I don't have any such solutions to recommend, to be honest. I'd be concerned about the wholesale obliteration of detail. Many of the proposed solutions seem more oriented to the heavy print lines that appear using the PLA process, not Shapeways acrylics.

These approaches all seem risky to me, as I don't see how much control you have over detail loss, and leaving things too long can simply melt the plastic altogether. And acetone's not exactly great for human health!

Other issues

Once you've got your parts cut and cleaned, you need to paint and glue. Here are some other key points.

4) Priming

Once cleaned and spotless, the next decision is whether to prime or not. Primer is a kind of paint designed to stick evenly to all surfaces, to offer a friendly and protective surface for paint, and to be fairly opaque. Primer is great for treating difficult to paint materials, for making the base model lighter or darker, or for making models made of different materials look consistent in colour. If you're applying aggressive weathering techniques it's often more convincing to scrape a model down to a primer of a preselected colour than down to plastic.

Some people advocate self-levelling primers, which are thicker paints that can flow in and level off uneven areas. These are often used for painting cars to compensate for minor surface irregularities. They work well, and can help fill in print lines, but too thick an application can obliterate fine detail.

Given the delicacy of the detail components I design, I don't recommend thick and heavy primers. Something like Tamiya's white and grey "Fine" primers are good, as they really are as fine as you can get. The dorkily named Chaos Black spray from the Games Workshop is pretty good too.

But always prime lightly! You don't need to spray on a ton of paint, and the Shapeways acrylic plastics take paint pretty well.

5) Glueing

The liquid solvent cements used for glueing styrene model kits together actually dissolve the plastic slightly. This essentially welds the two pieces together. But solvents formulated for styrene don't work on acrylics, like this 3D printed stuff. So you're best off using either superglue or epoxy.

Superglue

Superglue, alpha-cyanoacrylate, or ACC is the fast-acting liquid or gel glue that we're all used to. It works really well at bonding acrylics and other plastics together. It can form really strong joins - often stronger than the materials themselves! Most liquid superglues can't bridge gaps. But if you put down a bit of baking soda and then add the superglue, the soda hardens into a solid and easily sanded gap filler.

I'm personally not crazy about superglue. First, it's runny and tends to get everywhere, especially one's fingers. I find it a bit hard to control for that reason. It can easily fog materials, leaving a permanent white crust on things, especially on clear surfaces. (did you know that police detectives and forensic investigators use superglue vapours to make latent fingerprints visible and permanent?) Most types can't fill gaps, the baking soda trick notwithstanding. It can take a few seconds to set, though spray accelerants help a lot in this regard. And it can attack certain materials - destroying plastic fibre optics, for example. But its strength and ease of flow are both useful properties.

Epoxy resins

These are the two-part glues - resin and hardener - that come in two tubes or in separate sides of a plastic syringe. I find they work pretty well for glueing acrylic parts together or joining acrylics to plastics. They're messy and set fairly slowly, depending on the formulation (5 minute epoxies are considered fast), but since they're thick and sticky once mixed, they can lightly hold materials before setting. Blobs of epoxy can be easily sliced off if misapplied, and darker epoxy resins are easy to see against white or grey plastic, unlike transparent superglue which can be hard to see. A small blob of epoxy around the edge of something can bridge thin gaps and hold things in place well. Epoxy shouldn't fog plastics.

So neither superglue nor epoxy is perfect. I always have both around, and use whichever seems better for the task at hand.

6) Painting

As noted, the acrylic surfaces paint up well. You should be able to use acrylics, enamels, or lacquers as you wish. Though note that you are limited by the plastics of the base Bandai kit if you're adding details to a Star Wars model kit. Bandai's specific formulation of styrene will crack and split if exposed to the solvents used in oil paints, for example. Turpentine and mineral spirits are pretty bad.

These don't seem to affect acrylic 3D prints that I've seen. But it's wise to test your solvent-based paints and thinners on some scrap material first. It'd be pretty depressing to sink a whole load of time and money into building the perfect model, only to have it disintegrate and crumble at the final painting stage!

I've personally used Tamiya primers, AS sprays, TS sprays, and bottle acrylics without problems. I've heard that Tamiya PS products, designed for polycarbonate model cars, are bad for Bandai plastics but I don't know if PS paint affects acrylic prints.

For more information on painting plastic models, check out these other articles from a Gunpla hobbyist site:

http://otakurevolution.com/content/laymans-gunpla-guide

One other key thing to keep in mind is wax residue migrating out and causing a sparkly finish to appear on the surface of the paint. This is a problem with Shapeways "detail" plastics in general, but seems to be related to the amount of wax or oil on the surface. An important reason why you need to clean every bit of wax off the part, especially taking the time to scrape the rough areas with a knife, before painting.

7) Print issues

As noted above, the 3D printing process isn't flawless, and involves a bunch of human labour. In addition my models are mostly so tiny, with fragile components, that there is a real risk of breakage.

There are also printing artefacts, which can be rather annoying. Take the objects below that were printed as Smoothest Detail plastic. Note the diagonal print lines on the left-hand and central objects. These reflect the orientation inside the printer, and result in little ridges which are difficult to eliminate in flat areas, and impossible to eliminate in detail areas. Ah well.

These ridges, which aren't actual print lines, are the bane of printed users. Sometimes you get a perfect printed model that's smooth and amazing whereas other times you get a model that's totally covered in raised stripey lines. Notice the left and middle pieces below - they're striped with diagonals.

Is it a problem with a specific printer? A calibration issue? Orientation in the printer? I don't know enough about how these printers work to say. Shapeways have agreed to reprint some of my model orders which had extremely prominent raised lines, but have said that models with finer raised lines like those below are considered acceptable.

Generally, Shapeways are pretty good about replacing parts damaged during production or shipping. You just have to contact their customer support (though if you could let me know what happened as well for my own records, that'd be great!) and they should sort you out. Note that they won't do anything about a part that's been altered, painted, cut, worked on, etc.

Fit and finish

An important thing to keep in mind when working with these printed products is who designed them. I'm just a hobbyist, and I made these parts mostly for my own needs. I've made them available for others, but I'm not a commercial product designer with a big budget and access to official plans and models.

What that means is my models aren't going to be 100% perfect. I've worked pretty hard to make the details accurate to the on-screen appearance of the prototypes, based on extensive research, but I've probably made mistakes. Do let me know if you spot anything particularly egregious.

When it comes to fitting replacement components to commercial models, I've tried to get close and have spent a bunch of time and money on successive test reprints. But I can guarantee you that you will need to spend a bit of time filing, trimming, and cutting each part to fit. They may not always fit on the first try.

8) Pricing

Prices for Shapeways prints have always been high. And as of 2024, they're even higher. And, if you're in Britain, Brexit has made pricing even higher since the European print factory is in the Netherlands.

In fact, Shapeways are now prohibitively expensive for many products. I'm sorry about this, but there's obviously nothing a designer can do about the prices that Shapeways set. They have a complex and very difficult to understand pricing algorithm. It has many factors, including a high minimum price, and since it penalizes products with many separate objects it's often necessary to join a bunch of parts together on a treelike sprue. Unfortunately this means you then have to cut the sprue off, risking damage!

It's worth keeping an eye out for Shapeways' sales. Every few months they'll have discount sales, and sometimes offer free shipping for a limited time. If you're not time-constrained, load a few things into your shopping cart, and wait.

Of course this doesn't help those of us who are trying to iterate through a number of 3D designs to get something that works as an actual product! :)

In fact, you may notice that the prices I, and most other designers, charge is higher than if you were to print your own .STL files yourself. In my case I charge a small markup to recoup the significant development costs of making these designs. I have to do multiple test prints to verify the design works, and I don't get a reduced price on that from Shapeways!

So it's not hard to spend a bunch of money developing a design and, given the low volume of sales, it takes a long time to get that back. And that's not counting the hundreds of hours required to create a design.

The Future

Finally, note that the longevity of 3D printed parts is currently unknown — the technology just hasn‘t been around that long. We simply don’t know what shape they’ll be in in 10-20 years’ time. Or longer.

Hopefully UV-cured resin components will hold up okay, and not break down from exposure to UV or light over time. Painting with primer and good opaque paint should help by blocking UV. But chances are, like virtually all synthetic plastics ever made, 3D prints will become more brittle and thus more vulnerable to breakage eventually. Time will tell!