RepRap Prusa i3
In the leadup to our last hack day at REA I acquired a RepRap Prusa i3 kit from Aliexpress because one of the teams indicated a desire to build one from scratch. Unfortunately as the hack day approached a more important project (involving security and fraud detection) lured them away from the fun of building a 3D printer.
So it fell to me to reason through the instructions and get it working.
It doesn’t compare to the Ultimaker 2, but I feel like I now know a LOT more about 3D printing than I did before.