After several years of fooling around when drilling holes, I got a new rechargable hand held Dremel tool. It has a big flat area on the battery which is at the top when using the tool.

I stuck a bubble level (a round one that covers all directions) on to that flat area. Now I just lay the piece on a flat surface, fire up the drill, and eyeball the bubble just before drilling to make sure that the drill is square to the part.

Surprisingly accurate! Now I can drill motor mounts with great precision without the bother of a drill press. No need to get the exact drill for the job, just use the Dremel with a small drill for a starter hole, the right drill will follow that hole later on.