I've posted briefly about Lego Technic Frames to make enclosures. I've published a
detailed article at Jon's Imaginarium. If you have access to a laser cutter, this may be interesting to create custom enclosures.
One thing I have been noodling around for a personal project is a 19" rack enclosure. The Lego frames didn't lend themselves to the application because they don't line up well with the standard rack panel heights. Last night I saw the Lego 3x19 frame, which I never thought would be that useful....
Bingo. 1U height rack solution found! This frame would provide a 24mm internal height, but if that's not tall enough, the cover panel can be mounted on spacers.
If anyone is interested, I added SVG files to cut the pieces needed for a 1U 19"rack enclosure on Jon's Imaginarium.
Laser-cutting panels allow me to make panels that fit, the the needed holes accurately cut and positioned (my Dremel tool abilities to do so are sorely lacking!) Add the needed openings on these panels and you're good to go.