Not an original idea - these have been around for quite a while with ronco being the original as far as I know. I didn't see a printable version of these to fit the sleeved wera hex keys, so I modeled this one.

I used 18x4mm O-rings for mine because that's what I had, but a bigger size would work better. You will find that this is a much better holder than the one that comes with them - At least i find it frustrating to use because it takes a lot of effort to get each in or out.

I used PETG for general heat resistance and sturdiness, but PLA would work fine too.