Mask A Hole To A Smaller Diameter As A Reducer Ring

Ring Spacer

A spacer and sleeve you size yourself. Drop it into a cup holder to take a narrower bottle, slide it over a pipe or shaft as a protective sleeve, or use it between two parts to hold them a set distance apart. Set the outer diameter, wall thickness and height; every one is engraved on the outside with its own dimensions, so you can tell them apart on the bench.