This is a hexagonal key. The openscad source is provided, so it can be modified to be another size, with a bigger handle, etc... In particular, the tolerance can be modified, so the key is slightly smaller in order to make sur that it fits. The provided key is 0.2 tolerance (-0.2 mm on all sides of the key so it is actualy 11.6mm instead of 12mm). The size and the tolerance are printed on the handle. Note: I did not print this model yet. As soon as I get the chance to print it, I will comment on how I did. I made sure the overhangs are 45 degree max, so it should print easily.