I designed this for when there's not enough space on my those dinky little lecture-hall desks for coffee. It clamps on to anything between 10-20mm thick.
It's also quite useful for places like workbenches or porches.

It was field-tested with a full venti sized coffee from Starbucks, and held up fine.

I suggest printing the screw/wrench part with more walls, like 4 or 5.

If you have flexible PLA, you should print pads to glue to the toothed : parts: you won't have to tighten the the wrench as far.