A basic router jig for installing door hinges. STL file is for a 3.5in x 2.1in hinge with .1in depth and 5/8in radius. Using OnShape link, you can set hinge and router entrance dimensions using defined variables. These are slightly bufferd (.1in) to allow for tolerances of printing/routing. 

If hinge depth is correctly set, you can use the router entryway to set bit depth.

Print with ~20% infill. Assuming a 1/2in router bit, should be able to print without supports.

Link to OnShape model