Been working on various ways to shield SUT's over the past few years and I must say mumetal is a pain to work with. It cuts nicely with a paper cutter but getting holes in for RCA's and such is no small task. I went to the local hobby store and bought some 1/32" birch with the idea that adding some support to either side would allow it to be drilled easily. As an added plus the 1/32" spacing gives a nested effect.
Quad QA12/P Amplifier - This is pretty close to Quads first amplifier. I got to put my hands on one of these once very cool early British amplifiers. http://www.itishifi.com