This adjustable laser level is just the thing to make sure that oddly shaped items (like tumblers with a drop off to fit in a cup holder) are as level as possible in your rotary tool on a laser engraver.

It requires a 29x10x10 bubble level that can be press fit in the slot on top. No glue required (but optional)

Here's the level I used: https://amzn.to/43tqfnS (affiliate link)