Dowel drilling guide jig
For dowel joints the two mating holes must line up exactly, and this self-centering guide makes that repeatable. The jig is a 70 x 40 x 30 mm block with a channel that fits 18 mm stock, three 8.2 mm guide bores 32 mm apart for 8 mm dowels, and knurled indents so you can grip it while drilling. Print it standing on end with 100 percent infill on the guide section so the bores wear slowly, or press in brass tubing for heavy use.
Telling SpeakCAD your dowel diameter, stock thickness and hole spacing gives you a jig that matches your project rather than a generic approximation. If you switch to 6 mm dowels next week, ask for a variant in the same chat. The browser preview is free and works on any machine.
Model a dowel drilling jig 70 x 40 x 30 mm with a 40 mm wide, 20 mm deep channel for boards, three 8.2 mm guide bores through the top spaced 32 mm apart, a 5 mm fence lip on one side, and a 6 mm clamp slot.