I don't have any pics, but glasscages.com will make pretty much any size you want. I think tenecor will as well. Or your LFS may be able to custom order.
here is a 48"x24"x16" 1/2" acrylic tank i bought used,
the guy i got it from also has a 6'x3'x16" 1/2" acrylic running.
he said that someone by the name of Geo made them.