Biohazard Symbol

There's not a whole lot to say about this. It's a biohazard symbol in OpenSCAD, to the exact government specifications. I used this as a reference:

http://www.michigan.gov/documents/CIS_WSH_part476_54539_7.pdf

It's done in the 2d subsystem, so you can use it in 2d or apply a simple linear_extrude() to convert it to 3d.

The example STL and DXF files are 51mm across, which is the diameter you get when you use A=1 according to the spec; the OpenSCAD file allows you to easily specify th