You only pay for the drawings and not for the parts

The plans contain:

•    Plans for the marble machine (DXF file)
•    Plans for the modules marble race (DXF file)
•    Detailed instructions for assembling the machine and modules (PDF file)
•   Now  it is more common to use some form of CNC machining to produce the machine, so the DXF files for the machines are available and in some cases the 3D model files as well (Stl file)
• Including a lot of reality machine photos