As a preview to what this thing is shaping up to be, here is the gear motor and the new cam design. That new cam is what the bearings will be riding on to make the fitness device move up and down to fake it out. :)
The cam follower will snap through the inner hold in the bearing with something just like this:
It may take a few prints to get the tolerances right, but that's the concept. In this version of the Cheat-O-Matic, the follower will have a light spring damping the vertical motion so it doesn't hop up and down as harshly as the one in the video on my site.
Still a lot of CAD to do. This thing has a toggle switch for power and a port for a 12V DC plug. Hopefully the prints will come out nice and within tolerance and I won't have too much nylon fiddling to do to get the prototype working.
Talk to ya later!