Customizable Wheel for 28BYJ-48 stepper motor

I tweaked MarkBenson's design and took a stab at creating my first Customizer.

Use the Customizer to change wheel diameter, remove the spokes (customize wheel in Tinkercad!), add text, create a test-fit piece, or tweak the tolerances for a better fit.

Use a common O-ring for traction.

Full drawing robot project documented at http://www.instructables.com/id/Low-Cost-Arduino-Compatible-Drawing-Robot/