A rotating angel inside an open ball is rail car number eight in what (I hope) will be a series of ten, one published every two weeks until Christmas. This O gauge car (wheels, axle, coupler and bed are all 3D printed plastic) is part of an active train.
Start by converting a servo motor to a battery powered gear motor. Remove the four screws from the bottom of the motor.
Remove the stop on the gear.
Remove solder from the two tabs that attach to the motor.
Remove the electronic board, then remove the screw.
Remove pot from motor.
Solder wires to motor, then replace back and assemble with 4 screws.
Using a 3d printer, print the various parts. Print the ball at 120% size and cancel when it is 70% complete. Print the angel at 65% size.
Assemble the rail carrier and wheels.
Add the rail bed.
Add the bed caps.
Insert the servo motor, then solder the leads from a battery carrier (2 AA) to the motor leads.
Glue the angel to the servo horn.
Attach the battery case with velcro tape.
Glue the ball to the servo base, place on a track and let it ride!