Expression pedal

[buckle]

I'm still pretty new to the world of pedal building. I am trying to build an expression pedal from an a crybaby with the 100k hot pot, but want to put a switch to alternate between the treadle and a 100k pot I am going to mount to the side of the pedal. I think I can do this part, but it would be cool to add an LED as an indication to which pot is active. Would this require the use of a 3pdt switch?

[kothoma]

Would this require the use of a 3pdt switch?

Yes, a 3PDT would work:
1 pole for switching between lugs 3.
1 pole for switching between lugs 2.
1 pole for the LED.

If you could live with 50k resistance and a bit of a taper change, you could wire lugs 3 in parallel and only switch lugs 2. Then a 2PDT would suffice.