Metric Wrench holder - for the small sets you can get online (4mm - 11mm).
There are two versions. The improved version 2 holds the wrenches better - pegs are a
...Plus bit longer and angled slightly. It also has some better fillets and chamfers.
I'm still learning CAD but I think this is useful. I couldn't find anything that would suit my specific set so maybe this is helpful for someone else.
2019-01-11: UPDATED:
1) Added a raised-letter version which is easier to colour with a sharpie. I haven't tried printing with a different colour yet - but that's also possible (though that would mean the pegs would be a different color as well - might not be a bad idea).
2) Added a no-letter version so you can write your own letters/numbers and/or use this for Imperial or Metric
If you print, please post a make!! I'd love to see how this prints for other people!