So I've been making remote volume control for some time, using a cheap servo and the stock potentiometer for HL or Taigen. Unfortunately this in line configuration doesn't give full rotation, the pot having a 270 degree sweep, and the servo only giving 120 degrees. Enter a newly given 3D printer for my birthday, and having learned a little CAD on Fusion360, and finding an insert into the program to do spur gears, I've assembled this configuration which gives full travel:
The long M3 screws are 25mm long, you have to drill the gears to fit the pot and servo splined shafts, but be careful as you don't want to drill all the way through. When assembling, plug both the servo and the pot into the tank, and turn the pot clockwise until the volume just goes to zero, and using the transmitter turn the servo counter clockwise all the way and then pop the large gear onto the servo. Test to ensure it travels smoothly all the way to both stops. The cover keeps you from jamming any wires into the gears.
It fits rather well into a crook or cranny in the tank pretty easily.
I'll load the .stl files next post.
Jerry