For this midterm project, we manufactured 2 sets of LUCIA cervical cancer models, one 3D-printed and one casted in polyurethane for a total of 8 cervixes, to match the original set.
We first printed the models with a layer height of 0.16mm. As you can see below, this was not fine enough to achieve a smooth surface. Upon reprinting with a layer height of 0.1mm, we achieved the necessary smoothness.
We also printed the positive mold (of the combined models and box CAD files) using the same layer height of 0.1mm.
Next, we made a negative silicon mold and released after 24h.
We then cast it with polyurethane according to the package instructions. We did this step twice because the first iteration had many bubbles. The first time we used mold release and the second time we did not; it made no difference in how the casts released. To reduce the presence of bubbles, we cast the second iteration on top of the belt sander so that the vibrations would cause the bubbles to release. This indeed reduced the presence of bubbles.
A meniscus formed on the bottom, so we sanded them flat, as well as sanded off any imperfections. We also filled some of the bubbles that did form with filler primer.
Then, we painted them.
original, 3D printed, casted (left to right)
An improvement that could be made in the future is to paint the 3D prints and the casts at the same time for closer color matching.
Finally, we spray pained a clear gloss coat. 3-4 coats were needed to achieve a texture similar to the original models.
Here is our clean final work station:
and cost analysis:
| Cost Type | Cost | Price | Source | Quantity | Total |
| Materials | PLA | $0.10/g | ankermake.com | 0.2kg | $20 |
| Silicon | $44.08/2000mL | amazon.com | 400mL | $8.81 | |
| Polyurethane | $109.75/7570mL | amazon.com | 80mL | $1.16 | |
| Plastic cups | $5.06/100cups | amazon.com | 4 cups | $0.20 | |
| Popsicle sticks | $4.99/200 sticks | amazon.com | 5 sticks | $0.12 | |
| Filler primer | $19.98/28oz | homedepot.com | 0.5oz | $0.35 | |
| Sand Paper | $0.52/sheet | homedepot.com | 0.5 sheet | $1.02 | |
| Acrylic Paint | $6.99/12fl oz | michaels.com | 2fl oz | $1.17 | |
| Spray Paint | $5.98/can | homedepot.com | 0.2 can | $1.20 | |
| Labor | Prototyping Engineer | $36.48/hour | ziprecruiter.com | 2 hours | $72.96 |
| Design | Engineering and Development | $48.17/hour | ziprecruiter.com | 3 hours | $144.51 |
Total: $251.50
