The Handcuff Key for Chubb High security handcuffs as presented on the HOPE conference in 2012. This is the default "123" key-code which is used for basically all cuffs in actual use.
For 3D printer: try to get the filling as high as possibly - it's small and only 2mm thick, so don't worry about printing time too much. Best printed without a raft (on heated plate or whatever needed).
For laser cutter: use the DXF and simply cut it from 2mm acryllic glass. Lexan even gives a more robust key but is much more ugly to cut. From my experience acryllic keys work just fine as long as you operate them right.
You should know in which direction to turn and how often - but I assume all law enforcement professionals know their gear... ;)