Lay your check in the middle when you are ready to scan it. It makes the process easier so you don't have to look for a solid blank dark colored surface to scan on.

Outer Dimensions
3.94x7.24x0.24 | inches
100x184x6 | mm

Inner Dimensions
Fits a standard check

The stl is not in the right print orientation FYI. 

Brim is suggested. I used PLA but any filament should be fine. The standard 15% infill will also be fine.

Dark solid colors required. Black is best.