Catwalker

 The big mystery make project, what is it, can you guess? Will it work when I'm finished? It's desktop sized, and fairly complex, in fact, it's the most complex thing I've tackled to date, and I'm worried about it. Building it involves Stepper motors, wires, gears, a microcontroller, computer interface,  and lots of 3d printing and metalwork. This is a long one, so, give yourself some time.