We created this for the Elephant & Castle Mini Maker Faire. This is the full size model for an M16 nut. However you can shrink it down to fit an M3 nut and create an elf sized spanner like the ones we were giving away. Alternatively, blow it up and print a monster spanner for very, very large nuts!
Space on the handle has been left blank for you to customise with your name in OpenSCAD / Tinkercad.