Assuming it works... The structure holding the drill is two pieces of aluminum flatbar and eight bolts. Bought a long, mountain bike seat post to help reinforce the aluminum tube. Besides being longer than usual, the seatpost is 2/10 of a millimeter greater diameter than it's supposed to be, it's a very snug fit into the shaft. The simplicity and functionality of the drill holder is hugely better than the first bike. Barely tightening the bolts and it's a very sturdy fit. Some superglue might be added where the flatbar meets the tube, and maybe some hot melt glue to the drill handle area.
Next and last is making the trigger controller. On eBay, somebody wraps a bike handgrip cable around the drill and then around the trigger. But it might be done simply by connecting the cable sleeve to the trigger and securing the end of the cable just beyond the trigger (towards the back of the drill).
Someday, adding a spring to the drive train would be useful. As is, power must be engaged carefully.