>>340770Doing motorized conveyor belts isn't that hard. You just don't pour them in plaster of course. ;)
You could just take any cheap R/C tank or race car(replacing the wheel with treads from a toy tank), and it's pretty much just done. Flip it upside down, texture the bottom, and mount it in your table.
The only problem is that it would be pretty fast to play with. Might be better of buying a very low power motor and doing it yourself.
Then again, you are talking about playing pretend. With toys. You could just.....pretend that it works.