Lots of people have been making these for years, but here’s a video by Gryphern.
Non-electronic animated tail by Jinx_Tiger – I can’t find a reference to it online (Jinx’s technique goes back to 2004 or earlier), but it’s possible to make an animated tail that works purely mechanically. It’s the same general arrangement as what WolfTail does, with a string going up each side, but instead of servos doing the pulling, it’s attached to each shoulder instead. Move your shoulders and your tail moves.
Haven’t looked for guides yet, but here’s some ideas:
Wings that open and close – I’ve seen pneumatic done, could be motorized or hydraulic as well, but it can be done purely mechanically as well. Not everything needs to be electronic.
LED’s under fur
Breathing smoke – e-cig parts