I've made a 19" DIY rack for my homestudio:
It's 3U + 10U + 4U
and made of 2100 x 400 x 18mm wood panel from Biltema (biltema.no), plus a little this and that.
I misunderstood the concept of the 19" inner measure, so the first rack-rails I ordered didn't fit. Had to order the thinnest rails I could get -from the US.
Getting all to line up to square was also difficult, and especially getting the doors right.
Else I'm quite satisfied. The rack are fitting nice beside my PC, awaiting some more DIY-stuff :)