My latest terrain piece, some steampunk-themed rough terrain:
It's made from a piece of cork tile glued to a hardboard base, with lots of bitz glued on top. Here's a close-up of the detail:
The larger gears were purchased form a company called Green Stuff World; the tiny ones were from a lot of watch gears that I found on eBay. The tricky part is gluing stuff on in a way that looks cool, but doesn't prevent models from being able to stand on it. I think it turned out pretty well, aesthetically pleasing and functional.
I can also set old wreck markers (the inner part, without the outer ring) on it to convert it into cover-providing rubble.