After having to unthread and rethread your sewing machines several times a day, a stand-alone bobbin winder starts to look very appealing.
I had recently upgraded the motor in my White 568 zig-zag machine, so the old motor I removed was used to build this. In its essence, the winder is just a motor that is put in contact with a bobbin winding mechanism. I also chose to add a dimmer switch to control the speed of the motor. I had originally planned to have the motor swivel so it could be in contact with two different winders, as my White and my Kingmax use different sized bobbins. That was overly complicated, so I decided to dedicate this one to my white machine since it has much smaller bobbins and has to be completely unthreaded to use the built-in winder. Lots of careful thin coats of spray paint allowed me to get a nice smooth and bright color. Underneath its just plywood of various thicknesses. The motor is mounted on springs, so when the bobbin winder is pushed into it, the motor gives in a little and maintains good contact with the flywheel, even if it slightly wobbles. The paint on the surface that the motor rests on was sticking a little, so I added a bit of cardstock in between.
In the future, I would do a dimmer switch that has an adjustment knob and a separate switch. Then, I could save a good speed setting and just turn it on and off without speeding up every time.