Back in April 2000, we invented a new class of interconnection network topologies for use in parallel supercomputers: Flat Neighborhood Networks (FNNs). You can read more about them at http://aggregate.org/FNN/ -- the key property is that PCs are connected to switches such that any pair of PCs always has at least one switch in common. The tricky thing about FNNs is how hard they are to design. We actually use a genetic algorithm to design them... but now you have the chance to design them by hand as a little 3D-printed puzzle (which we originally made for our research exhibit at the IEEE/ACM SC15 conference).
Typical FNNs connect hundreds of PCs and switches; this model has just six PCs and six 3-port switches. Your task is simply to connect all the switches to the PCs to form an FNN. It's harder than it looks.... ;-)
A very straightforward print in PLA. More fun if you use different colors for the switches.
We also printed them on a Wanhao I3 without any issues.
The PCs have a bump pattern on their sides that makes it obvious which PCs must be on the ends, but the order of the inner 4 PCs is not obvious. The same is true about the ordering of the 6 switches. Beyond that, each of the switches looks similar on the top and bottom. That yields 4! x 6! x 2^6 = 24 x 720 x 64 = 1,105,920 possible ways you might try to assemble them. Well, at least one of those ways works.... ;-)
As a hint, the order in which the PCs print works.