Smart Knob.

It's a battery operated knob for controlling volume of my home cinema setup. Will connect to Home Assistant, once I figured out the electronics. Wireless, of course.

BOM:

• 1x bearing type 6810 (50mm ID, 65mm OD, 7mm thickness)
• 3x Keystone battery clip 209
• 3x Keystone battery clip 228
• 1x rotary encoder with 7mm mounting hole, 6mm knurled shaft (the cheap amazon kind)
• 2x M3x15 bolt (button head) from the battery compartment up all through the stack
• 2x M3x10 bolt (button head) from the ring clamp up to the top
• 4x M3x15 bolt (button head) for connecting ring gear with ring
• 8x M3 nut
• two component (addition) silicone, Shore A50 or similar for the feet
• 1x Wemos D1 mini or something similar for connectivity
• 1x low drop linear 3.3V regulator for maximum efficiency while CPU is sleeping

Entire stack of printed parts from top down:

• top_audio
• ringclamp / ring
• ringgear / gear
• ringbase
• bottom
• battery door

Should be pretty straightforward to put together. Some hints:

• ringclamp and ringbase clamp the bearing from the inside
• ring and ringgear clamp the bearing from the outside
• ringclamp holds the encoder (mounted from the top, pointing downward)
• remember to put the nuts in ringclamp part before connecting it to top, or you won't be able to screw in the last two screws from the bottom within the battery compartment
• the keystone battery clips push in from the top, alternate the two types for easier wiring (batteries have to go in series)
• to mold the silicone feet, put the mold over the bottom of the bottom part, turn it so the cutout aligns with the battery compartment, make sure to press it all the way on to have no gaps, pour in silicone from the top into the two grates at the sides of the battery compartment. you want to fill the two compartments about half way to get solid silicone all around it

No information on electronics and code because I didn't get around to finish that. Feel free to use your favourite microcontroller, radio and voltage regulator. ESP8266/ESP32 and low drop linear regulator recommended.

First, I designed the non-printed parts and placeholders (bearing, encoder, batteries) and put them in places I found would fit, then I designed the different parts around them. Always checking by enabling/disabling parts that I can actually build the thing (i.e. get to the screws in partially assembled state, add more parts etc.).