I've been spending the last few months' evenings quietly working on a robotic tail design that finally feels pretty good to wear and control! Originally made for Tomorrowland 2020 (until that couldn't happen anymore), it fits in a regular dress shirt or t-shirt, and can reach the full up/down/left/right extremes. It lights up with 72 individually addressible LEDs. You can see a demo of it moving about and doing tail things at https://youtu.be/ivVPN2FsMvQ and a look at the lighting at https://github.com/acrylic-origami/.....img/lights.gif . Lots more pics and technical descriptions at https://lam.io/projects/tail/control/ & https://lam.io/projects/tail/build/ .

Briefly: it's a 3DOF arm powered by a geared BLDC at the base and two high-torque standard-size RC servos. The hand controller generates waypoints for tail *tip* position, so one can move the tip somewhere specific. All the control runs on a STM32 microcontroller.

Apologies for the terseness of all the descriptions — one of my main design goals was for this to be easily reproduceable, e.g. such that a hand drill and screwdrivers sufficed for its assembly. It's just a matter of refactoring some code and recapturing some shoddy process pics. Presentability, y'know.