This is a sturdy little tap holder I printed when I purchased an M5 tap from McMaster and subsequently realized that holding a tap with a pair of pliers is a miserable thing to do.Tap is held in place with a #2 x 0.25in Plastite screw, though the set screw probably isn't necessary.  If the fit is tight (it should be...),  warm the end of the tap over your stove and then press-fit it into the holder. Don't get it hot enough that you damage the heat treatment!Source files are included so the hole can be modified to fit other tap sizes.