Jim, you crack me up! It's good to see you back in action, my friend. Take care of that arm, please!
It's free, although if you want to tip the guy I'm sure he wouldn't mind. It's an STL file, a 3D model that you bring into a slicer (also free) that separates the file into layers and spits out a gcode file, which are movement and other instructions for the 3D printer. Your friends should know what to do with the file.
EDIT: Windows 10 has some free 3D tools if you want to see and play with the file...