Hello, I have been unable to find spacers online that have a small shallow channel for o-rings on the top and bottom of the spacers.

At first I thought about using a 3d printer to print the spacers with channels in them with ABS but the 3d printing forum I reached out to said that was a bad idea, that prints aren't water/air tight and they would need supports on the bottom where the print is attached to the bed which would leave a rough surface there.

Now I am wondering about buying the spacers and trying to either use a hole saw or a cnc router to cut the insets in the spacers. My big worry is finding a way to hold the spacers in place so they don't move while cutting the shallow insets with either a drill press or a cnc router.

I would appreciate any advice and experience you guys could share.

Thank you

Bob