I've thought about the inflation problem, I think I have a solution but I would need a very accurate 3d printer that could print in wax. Anyway no I don't know about any and even the inflatable dog ones are pretty manual and probably have the wrong feel (I don't own any, I just assume so from their design).
Now could I make the design I am imagining at a good price? Probably not. It would be like $600 of labor and materials. (and that is going up 20% per year right now)