If you want good speed control use a cheap corded drill and a router speed controller from Harbor Freight or something similar. Then you can use a nylon zip tie to activate the trigger on the drill, be sure to secure the drill from spinning before letting it go or it could get really messy.
The pictured drill has an RPM dial, set to "low", and a trigger-lock. 10A 1/2" slow-speed D-handle drill, Harbor Freight, $34.