I always wanted to do it but balked somewhat at the size of the motors, batteries, RC equipment, etc. to fit into the 1/72 Revell PT boat, the Tamiya Vosper MTB or the 1/350 ships.
Anyway this is the final idea.
I just bought a 10 pack of cell phone vibrator motors for $9.90 from Princess Auto, a Canadian hardware and tool place that has a good section on salvaged equipment parts and components. Cutest little motors I ever saw. I'll have to remove the unbalanced weight (that's the vibration generator.)
The motor has the diameter of a pen barrel. The motor itself is 5/8" length, has a tiny 1/4" long shaft extension and a pair of 1/2" contact leads. The motor's contact leads are a pair of sprung fingers that can easily be pressed onto a PCB (prototype board or custom made). The motor's plastic housing has a flat side. It will therefore be quite easy and convenient to mount the motor on a PCB and have the sprung leads touch conductor pads and that connect to a mounted battery pack and other electronics on the same PCB.
I envisage that I can remove the servo motor from a RC unit and resolder the leads to the trio (or quartet) of cell phone motors and power all the "scale" propellers in a multi-shaft boat. This way I will have full RC forward and reverse plus speed control using commonly available servo circuitry. The motors are so tiny that the servo circuitry should be able to handle the power draw. I am quite impressed by the motor's output on just one AA cell. Speed is not important, just the ability to make everything fit into a electronically and mechanically compact and light package.