This a very homemade, to spend the less money possible, and I had nothing to do on the weekend ...
Thanks for the the input, I really like the scale wheel used in Boomerang® Wholly RollerTM
the box:
Two parts, top and bottom cover and a piece for side, I used the gas stove for bend the acrilic-side.
support for potentiometer axis
I used a similar long-pot 47K
For the wheel...
The wheel I made with spray cap, the rubber removed from a Car wash machine
And extra cable, for external use of pedalboard.
a positive point: the box is pretty resistant, for foot use.
The down point:is the long way to get the clean, to max-dirty signal