I have a norton 4000/8000 grit waterstone that I use for most of my finer sharpening.  It is a good stone, but requires soaking before using, needs frequent flattening, and you have to squirt water on it often when sharpening.  I have made many messes on my bench while using the stone to sharpen and decided to try something else.  Operating it at the sink makes the most sense.  I had a long piece of UHMW plastic that would make a good starting point for a waterstone saddle.

The plastic is rigid, impervious to water, and left over from my table saw conversion (aka free).  The tricky part was how to hold it down.  I want it to be removable so screwing it down wasn’t an option.  I went around and around thinking about it until I just printed something.

Two of these funny hook shapes sit really snugly on the top rim of my garage sink.  A dab of hot glue on top held the plastic plank in place temporarily.  I flipped it over and screwed the hooks on from the under side.  You can screw into UHMW plastic, but you want to pre-drill and not over tighten.

With a really solid platform established I printed some cleats to keep the stone in place.  I used the same hot glue trick to tack the cleats so I could drill and screw them without any sliding around.

I have used this a few times since making the saddle and it works well.  I might add some kind of lip to keep sprayed water and swarf from dripping outside of the sink.  Otherwise this keeps the waterstone in its natural aquatic environment.

While I was working on all of that I printed a rag hook that clips on under the lip of the sink to keep an old shirt nearby but out of the way for drying hands.  Printing fixes everything.