Today I decided to determine if it was possible to vacuum form ABS using a 3D printed mold buck. Probably more of us have access to a 3D printer than a CNC router. This method allows you to design exactly what you want to mold in 3D ensuring that everything will fit.
I am happy to say that I was able to get a nearly perfect enclosure using 1/8in ABS molded over a PLA 3D print on the second try.
For more details you can see the build thread I am using this enclosure for.