Introduction:

Fossil life is incredibly diverse, spanning distinct periods marked by unique fauna. Due to its widespread interest and the geographic dispersion of fossils, obtaining specimens for educational purposes can be challenging. To address this, many universities have adopted 3D scanning and printing technology to create detailed fossil models.

This guide provides an introduction to 3D scanning and printing fossil specimens for educational use. It outlines the methods employed in the study Applications for 3D Scanned Ordovician Marine Fossils, which focused on six species from iconic Ordovician taxa, including trilobites, brachiopods, and gastropods. This manual provides a detailed overview of the process for producing accurate 3D models of fossil specimens.

The equipment for 3D scanning includes a smartphone, Polycam app, and turntable, while the 3D printing will be done using Prusa models MK1 and MK3s - 1.

Methods:

3D Scanning - The first step in the 3D scanning process is selecting ideal specimens. Fossils should be well-preserved, with minimal alterations, and large enough to ensure a high-resolution scan. Smaller specimens may result in lower resolution, while larger ones, though more challenging to scan at high resolution, are still feasible. The selected example specimens include several trilobites, with two Isotelus samples from the Limper Geology Museum and two Flexicalymene meeki specimens. Two brachiopods were chosen: Hebertella subjugata, representing rounded brachiopods, and Strophomena vetusta, representing flat-shaped brachiopods. One gastropod species, Cyclonema humerosum, was selected. Additionally, an assemblage of smaller fossils, Calymene meeki, was included.

Once the samples are chosen, preferred software of choice needs to be determined. The example specimens were 3D scanned using a phone application called Polycam. Although there are alternatives, some which are better, an introductory approach is used with this application. 

For optimal scanning of these fossils using the 3D Polycam app, it's important to use a flat surface with minimal shadows. Shadows can distort the scan quality, so overhead lighting is recommended to reduce shadows and ensure a clear, high-resolution scan. A turntable is required for capturing a full range of angles when scanning specimens. The size of the turntable should match the size of the specimens, to accommodate a wide range of sizes for both scanning and printing, a larger turntable is recommended.

Once all specimens have been chosen and equipment obtained, scanning can begin. For a good resolution scan around 90-100 photos need to be taken from several angles. If fewer pictures than required are taken, the scan will be low resolution. Conversely, taking too many pictures can lead to the same issue. The angle at which light strikes the specimen will vary based on its size and morphology. Some specimens may need to be stabilized with putty to ensure that all angles are captured for a fully rendered 3D model. For larger fossil specimens that cannot fit on a turntable, scans are taken while orbiting around the specimen. It typically takes 2 to 3 attempts to achieve the best renders. Once the rendering is complete, the files can be uploaded to the application Sketchfab.

3D Printing  -  Once all the scans were uploaded they were taken to 3D print at Miami Universities maker space. The fossils that were chosen to be printed for the example were. Herbetella subjugata (Brachiopod), Calymene meeki (Trilobite), and Cylconema humerosum (Gastropod). The 3D printing process requires the scans to be exported to the 3D printing software Prusa. 

In Prusa, the settings of each print must be chosen to create the best resolution and the preferred size. The time it takes for printing is dependent on the size and resolution of the print. A two inch long print at 0.15 mm (a measurement of resolution) would take around two hours of printing. A print five inch long at the same resolution would take around six hours. Improving the resolution can be difficult due to the highest resolution setting taking nearly ten hours to complete. 

The printer uses a flat surface from the surface as a base, because of this some of the scans will have issues with printing. Scans of fossils such as brachiopods can be rather difficult due to the lack of a flat dimension to use as a base. The best approach is to create a flat pedestal within prusa to support the specimen, allowing the program to easily recognize the object's base. Once all of the desired settings have been selected, the 3D printing process can begin. The Miami Makerspace primarily uses the printer Prusa MK3s - 1, however for smaller prints will use the Prusa printer 1.

Results: 

Below are the finalized 3D scans and 3D prints used in the example study. Figure 1.0 shows all the QR codes resulting from 3D scanning. Figure 2.0, 2.1, and 2.2 are the resulting 3D prints created at the Miami University Makerspace. 

Figure 1.0: QR codes for 3D Scanned fossils. Link to Sketchfab. 

Discussion: 

Each 3D print of the scans was successful, but there are several areas for improvement as the user gains more experience. All scans are missing a dimension which can be fixed in multiple ways. Many programs can be used to edit the scans in post to ensure a better print. Examples such as blender are mainly used in the 3D modeling field. As noted earlier the flaw of losing a dimension is a major downside to this method. While using a pedestal is the most effective approach for this issue, it does not completely eliminate the potential loss of detail. 

The 3D printing process went through many stages where adjustments were made to create the 3D prints. The filament color is chosen by the user, but for fossil specimens, a shade that is neither too bright nor too dark is preferred. In this example, a beige-tan color is used to highlight details without oversaturating the print. All prints are defaulted to 0.15 mm resolution in Prusa. Using a higher resolution often increases the chance of print failure, with the model losing its shape in the initial stages of printing. The finalized prints in this example study were at 0.07 mm which was possible due to the globose shape and smaller size of these prints. A more intricate and detailed shape increases the likelihood of printing failure. When 3D printing the ability to increase the size of fossil specimens is also possible. Figure 2.0 shows an excessively large print of Hebertella subjugata compared to the original specimen.