Not too much to it: depends on what materials one has around. Mostly one needs a frame to hold the "drum stick" and that turned out to be a wooden spatula  for me. Drilled a hole in the spatula to mount it on the rear guitar strap peg and locked it on with a strip of vinyl. 

Drum stick (chop stick) was epoxied into a fishing pole tube set inside another tube which was cable tied/expoxied to the spatula mount. A rubber band provides some tension for retracting the drum stick. 

Wire connected to foot provides power to pull the drum stick. 

Now I just need to develop a good sense of rhythm.