How to 'finish' 3D printed parts

Depending upon which method of 3D printing is used (Filament or SLS Resin) will alter what you need to do and how you finish the parts. SLS Resin printing is more accurate but typically can only print smaller parts. Filament 3D printing is used for larger volume parts but the surface quality is not as good as it requires a little more 'finishing'.

Once you have your parts you will first need to remove the support 'scaffold' structure using a pair of specialist 'snips'. These are sharp and can cut very close to the surface of your parts. You may need to use tweezers or even a scalpel knife for very fine areas.

Once you have removed the scaffold support structure you then need to carefully clean up the parts by using a mixture of Needle files (very small files) and abrasive paper (Wet and Dry). You will need to start with either 320 or 400 Grit and work your way up through the grit number (1000 or 1200) to achieve a perfect finish, ready to be spray painted.

Spray Painting

To prepare your 3D printed parts for spray painting (using Car spray paints) you need to try and make sure that the surface is free from grease and dust and has no imperfections. Then you need to mount your parts onto a piece of flat sheet MDF / Plywood. To do this you will use some White Tac to raise the part off the flat sheet (this is done so that the paint will not stick the part to the flat sheet).

You then need to prepare the surface of your parts ready for colour spray paint by add one or two coats of Primer spray. This is usually Grey, Yellow or White (if you intend to car spray a part white or yellow as a final colour) primer. The primer spray provides a good, even coat of colour ready for the car spray to sit on. You will need to spray your parts ideally with at least 3 coats of paint - note that expensive German cars (BMW, Mercedes, Audi) typically have 12 coats which gives the deeper colour.

Once your parts are dry you can then spray a coat (or two) of clear lacquer. The lacquer will give the sprayed parts a glossy shine and also add a layer of protection to the part.    

Once you have sprayed all of your parts you are then ready to assemble.