Tap alignment guide block
Starting a thread tap perfectly square is the difference between a usable hole and a ruined part. This guide block sits on the workpiece and holds the tap shank vertical while you start the first turns. It is a 50 x 50 x 30 mm block with stepped bores for M3 through M8 shanks, each 0.2 mm over nominal, plus a 90 degree V notch on one side for tapping near round bar. Print it upright with 100 percent infill in PETG or ABS, since taps are hard on plastic.
With SpeakCAD you enter the shank diameters of your own tap set rather than accepting a preset list, and can ask for extra bores or a taller body for long taps. Iterating happens in the chat and viewing the result costs nothing.
Design a tap alignment guide block 50 x 50 x 30 mm with five vertical bores for shanks of 2.5, 3.2, 4.2, 5.2 and 6.2 mm, a 90 degree V notch on one side, chamfered edges, and engraved size labels beside each bore.