No drill press? No problem! Just pop the diameter of your drill bit shaft into this parametric bit of open-source magic, modify whatever else floats your boat, and hit print! The problem with other drill guides is that (I dunno 'bout you) but all my drill bits are of differing diameters! No problem here.

A few words of advice. There are two objects that spit out from the program. R click → split → by object. Move the little ring out to another plate, test fit him on your bit, then print the whole thing out. Don't print the whole guide out without a fit test - if it's not right, you'll save time & filament by changing the width a little bit to get it right! You want it supported, but not tight. This program accepts millimeters only - multiply your empiric shaft bit width by 25.4 to get the mm!