This is a magnetic hex key tool holder for the sort of hex keys that accompany many power tools. The design is parametric so it can be adjusted to fit the specifics of your hex or other keys. This is version 1.1. For those of you that snuck in and made 1.0, this version uses roughly half the material and 1/3 less time than 1.0, and in my opinion looks a ton better aesthetically with the nice curves. Print it with the large thru hole oriented vertically. On my printer, a SnapMaker A350T, this did not require supports.

As is, without adjusting any of the parameters, it accommodates mounting magnets, mine are ¼” in diameter and 1/8” thick. The hex key, mine is a nominal 1/4" hex wrench, is slightly less than 7mm in diameter. The widest dimension of a hex key is more than it's nominal size since you're measuring the hypotenuse of a triangle, which is longer than the long leg.

The photos show the holder as built front and back and in place on my Rikon bench top sander.