I got my 3D printed detent bumpers, and they seem to work fine.
Shapeways doesn't allow offering products made of TPU directly in their Marketplace - I would have to set up and link an Etsy account, with additional listing fees incurred, plus every Etsy order would be charged to me by Shapeways. It's all just too much of a PITA.
However, I've found a possible alternative: i.materialise.com. They look much cheaper too - about $30 for the sprue of 24 parts (which is two more than my tool tower set needs).
But since no one has said they want these detents, I'm not going any further until someone does so. Reply here if you want the "dog bone" shape shown in post #34 above, or any of the others. For other styles I will need one to measure and model first, even a broken one as long as all the parts are there and fit together reasonably well.
If these replacement detent bumpers become "a thing", I'll start a new topic just for them.