ER40 Collet

ER Collets are best made of steel, of course. But sometimes you need an odd size or shape and cannot find a supplier. It happened to me recently. I needed an ER40 collet which would hold a reamer with a morse3 taper. So I drew it up and printed it with PLA Rapido. Worked like a charm. The internal hole could be shaped to hold square, hex or rectangular material, or even a chess piece.
Mine is printed in PLA, and worked best when the small end was the surface attached to the build plate. Also needed internal and external brims, and supports for the circumferential slot. And 100% infill recommended.