Before selecting an impossible object to reproduce 5 time, I decided to learn a little bit about the types of geometries that are best suited to 3D printing, and the respective challenges associated with them. To do this, I chose 3 different impossible objects from Thingiverse and attempted to print them.

Each part was chosen because it presented a unique challenge, usually associated with the feature that allowed it to be categorized as an ‘impossible’ object.

Nested Pyramid: This object presented a challenge due to its complex internal geometry which would be impossible to produce from one piece using traditional manufacturing methods. Using traditional methods, this object would have to either be made from many smaller pyramids and carefully joined, or somehow be carved internally through some tiny incision which was later closed – both of which would be highly impractical. Using 3D printing however, the tiny details of the geometry may be compromised at the required size specified by the project.

Cube Chain: This object would be difficult to produce because it involved two objects chained together that cannot be removed without breaking one of the cubes. Using normal methods, this would be impossible to make. The challenges associated with this object were required supports, which would be somewhat difficult to remove.

Mobius Bangle: This object combined some elements of the pyramid-ception and cube-chain objects, having both complex internal geometry and connected links that would be impossible to make with other methods without breaking parts of the object.

For all of my initial prints, I used the recommended specs (0.15mm layers, 1mm wall thickness, 15% density). The results are pictured below:

Pyramid-ception: Big success! Absolutely no issues with the first print, which was especially impressive considering the complex internal geometry that was obtained at the reduced size. This object could be printed with no supports because its structure it inherently self-supporting. The pyramid shapes are also ideal ideal for a 3D printer as they are essentially mitered edges (rather than curved). This was the object that I was decided to produce 4 more copies of.

Cube-Chain: Some issues here with removing the supports, of which there were a lot. I struggled to remove the supports, as the cube edges were very brittle, and thus were barely stronger than the supports, and eventually one of the cubes broke in several places in the process. Although, after the supports were finally removed, the remaining object was ~technically~ still an impossible object!

Mobius Bangle: The problem with this object was also related to the supports, but this time the root of the issue was that the supports were essentially impossible to remove. I managed to remove the loosely attached supports from some of the holes, but the remaining supports were so entangled into the loop that they were too difficult to remove with the tools I had on hand. If I were to reprint this, I would likely print without supports and either slow down the printing or change the printer settings to improve the structural integrity of the object.

The remaining 3 prints on the Prusa printers were free of issues. The high level of detail and sharp edges were repeated very nicely. One observation I did make, however, was that the blue PLA seemed to be slightly more brittle. A few of the pyramids on the bottom broke off quite easily, where as the other colors did not have this issue.

My final print on the resin printer went smoothly, although it was less efficient (took about twice as long) and produced a less detailed print than the PLA printers, as can be seen below.

The resin printed pyramid seemed to be somewhat sturdier, but this was likely due to the fact that many of the small pyramids had fused together in places that had not fused on the Prusa printer.