Inspired by Tubalcain's video, but lacking a milling machine or nice chunk of steel, I cam up with this. It works on my Record Power 8inch grinder (RS8GB) but probably on any 6" or 8" bench grinder with a relatively shallow (3-8cm) tool rest.
Based on a 12mm diameter 1CT diamond dressing tool from Amazon for £8 (link below)
Rigidity of the PLA printed tool far outweighs that of the standard tool rest on my grinder. You have to actively avoid putting pressure on the tool/rest to stop it bending in towards the wheel. Small light passes and it works well.
It holds the 12mm tool shank surprisingly well without any kind of retention. I had assumed I would need a drop of superglue, hence the design of the separate knurled collet which could be single use (and has a slightly smaller bore for interference fit).
Threads are based on M16 x 1.5 (ie fine) but tweaked to give printable tolerance. As ever with 3d printed threads, trial and error, a dab of lube and some careful running in seems to be unavoidable. Print the test thread, I would start with the guide part scaled to 102% in X/Z planes only in your slicer and work back if required. (ie scale the dia. not the length of the thread or it won't fit)
Beware that given layer orientation and thin wall of thread, it will break if screwed in without the steel shank inserted if your thread tolerance is tight. If redesigning I would base on M18 or M20.
Printed in PLA+ threads vertical (ie the wrong way for layer strength) minimal fan and quite hot. I was going to modify following prototype print but only broke one threaded pin in testing.
Sourcingmap 12mm Dia Shank 14.8cm Long 1.0CT Diamond Dresser for Grinding Wheel
https://www.amazon.co.uk/dp/B00LUS0DP8?ref_=ppx_hzod_title_dt_b_fed_asin_title_0_0
The author marked this model as their own original creation.