IKEA Glass Marker

This is a small marker that fits on top of the common POKAL IKEA drinking glasses. Print it in different colors and/or write people's initials on the flat top, plop the marker on the edge of the glass, and voila! No more discussion of which glass belongs to whom. The stairsteps on the inside allow for the surprisingly large difference in glass thickness - press the marker down until it grips, if you try to force it all the way, it will eventually break.

If you're proficient with OpenSCAD and have a decent printer, you can also print up to four letters into the flat side. However, you'll need to adjust the kerning yourself.

It's not the prettiest code, but it works.