Chuck Key Holder

This one is sized to fit a chuck key with a 5/16 inch handle. Scale it up or down as needed. Attach these to machines with two sided foam tape as it makes for better adhesion on irregular surfaces.
These are available from DigiKey but they never seem to have this size and when they do I have to buy 100 of them. No more! https://www.flickr.com/photos/steamboat_ed/3275799170/in/album-72157613636548203/