I have updated the Heater Switch section of the 12VUpgrade document to include how to make a bracket for the Potentiometer and knob. This DC Motor controller is THE way to go. No heat is generated, the linear knob gives you total RPM control, and there is nothing Cheap feeling about it. Works with 6 volt motor/reducer even better with 12v PM354 Motor.

http://devestechnet.com/Home/Native12VUpgrade#heatersystem
or
http://devestechnet.com/Home/Native12VUpgrade#SwitchBracket

I am not sure how everyone feels about lighting. Is no lights on your Heater control a big deal? If lights would be nice, there is room on the bracket to put an LED or two under the knob out of site as a backlight system, but then it would mean bringing power to that bracket which at the moment isn't part of it.

Deve

1950 Chevy 3100 Deluxe Cab
1950 Chevy 3100 Standard Cab
In the Stovebolt Gallery
The Think Tank
More info and tips at Deve's Technet