Tasked with making an impossible object, I spent some time deliberating on what to print from Thingiverse. I finally settled on printing a set of interlocking pyramids. This object is impossible to fabricate due to interlocking geometries:

Photo: https://cdn.thingiverse.com/renders/a1/5e/d8/f8/a5/IMG_0028_display_large_preview_featured.jpg

I knew the best way to print one of these objects would be on the wetlab printers because there would be support material on the inside of the object that would be easiest to remove by dissolving it out. Bu, I was curious to see what the free printers could do and so I try it out. Once the print finished I was delighted to see a clean print on the top of the structure, little did I know of the mess that lay beneath. I had printed this object with a raft  to account for the very small contact area with the build plate and when i pulled it off the bottom of the object, it ripped the tip off of one of the pyramids. This was surprising at first but looking back on I had noticed that one of the pyramids that was contacting the base was not printing well, but I had the let the print run because I was not sure where the issue was. Besides the broken pyramid tip, the base of the object was also much lower resolution that the top, with the base layers poorly fused together. As a proof of concept I did manage to pull out the support material on the inside with a pair of pliers, but it took a long time and did not look sellably clean.

I tried again on the flash forge printer, lowering the layer resolution to 0.1mm. This print turned out better, but still had the same issue with one of the pyramid tips not being properly printed. At this point I weighed printing the object on the wetlab printers against changing my object. I went with choosing a new object to print because I was concerned there was a problem with the file (The free printers handled all the other base pyramids fine but one) and I didnt want to waste material on the wetlab printers.

In my quest for a new impossible object to print, I was inspired by a shark clip that was among the numerous example objects in the 3D printing area.

This object is impossible to print because it has interlocking parts at the jaw that allow for movement of the lower jaw but keep the clip as a single piece.

I was curious to see if a scaled version would  still work as a clip. I ended up scaling the print to 18% and printed with 0.2mm resolution with no support material and a raft because I was concerned some of the finer detail sections would not come out well. The raft was a mistake, as it was difficult to clean off the base of the print and left a rough surface but the object turned out well and the clips worked surprisingly well for their size.

For the final version I printed with the same settings and without a raft. I noticed that the clip jaw would get stuck in certain areas while messing around with them and I diagnosed the problem as some poorly adhered material on the inside jaw piece that I managed to clean off with a utility knife.