I made a solder holder a little bit ago but wanted to keep it out of my way when not in use. This shelf mounts to the wall with keyholes and screws. The keyholes are 12mm wide and 4mm deep. I included small recesses in the model to allow for small rubber feet on the bottom of the holder ( I just used a dab of hot glue in each corner, then set it on some wax paper to flatten them out and level them, to create some feet for grip). With the print orientation you may have to clean up a few loose strands on the front lip, but it will make for a very snug, almost snap in fit.
The author hasn't provided the model origin yet.