Hot to design 3d printable soldering stencil

Instructables user rmd6502 made a detailed tutorial how to design a 3d printed soldering mask for your electronics projects. he goes from Eagle EPS to PDF format, then PDF to DXF and then uses OpenSCAD to get the final STL.

He writes:

This is a neat way to save a bit of money when you order boards. Normally you pay an extra $25-50 for a solder stencil, either a silkscreen or a sheet of metal with holes where the solder paste needs to go

Detailed guide can be found at:

http://www.instructables.com/id/How-to-3D-print-a-solder-mask/?ALLSTEPS