Hardware and Tools - Printing in Plastic: Build Your Own 3D Printer - page 23

Spade and twisted drill bits will do the job, but for better results, you might consider using brad
point bits (also called spur bits) for straight-through holes. Brad point bits, like the ones seen in Figure
2-16, have a sharp point on the end.
Figure 2-16. Brad point bits provide better results than space and twisted drill bits.
When you are marking your plywood pieces for drilling, we recommend using a sharp transfer
punch like the ones shown in Figure 2-17 to create a small dimple to mark the centerpoint of the hole to
be drilled. These transfer punches come in various diameters for inserting into previously drilled holes
(match the diameter of the hole to the punch). If the fit is good, the punch will mark a dimple in the
center of the hole.