If I am not wrong you are talking about these:
Using Steel Studs: About Steel Studs
Those might work, but I have suceeded in building the frames for my traps out of these:
http://www.doityourself.com/invt/5370986
It's called corner beading, available in vinyl or metal versions.
It's thin, easy to cut, very light, full of holes (so sound can be absorbed from the sides as well), relatively strong (considering it's thin-ness), provides a rounded edge and quite cheap. Great material for framing DIY traps.
good luck
