This Gridfinity compatible holder has four spaces in a 1x1 holder. The front two are 8 units high and the back two are 12 units high - perfect for a few pairs of tweezers and a feeler gauge - these tools are always right beside my printer, so I made my own storage just for them.

Other makers have found these useful for assorted tools like cotton swabs (q-tips) and toothpicks as well!