First off, you need one of THESE for getting a hold on the string down inside the slot.

Next you need one of THESE to slip over the knobs.

Then you get one of THESE to spin it with. (Many styles available)

(You may need an adaptor to "chuck up.")

One or more of THESE will make everything neat.

(Just foolin' with you, although they might help if you don't find what you're looking for.

John