I use something similar on drain cleaning machines. Check with either duracable or ridge tools (ridgid).
http://www.ridgid.com/Tools/Products/
http://www.duracable.com/
There is a schematic in the duracable catalog, p. 84, item 10 is the footpedal assembly. Part number 25073K
Both will carry the footswitch. Typically a rubber or rubber with metal housing. The ones with metal housing are less prone to cuts, etc., but may slide on a deck and prone to rust. If you can blow in it to activate, you obviously do not need the switching mechanism itself, which they also carry. In a pinch, I have used an ear bulb (for cleaning ears, etc.) inserted in the tube! Good luck!!!