My friend was telling me about a new chicken coop she was building and then mentioned how inexpensive it would be to make as an outdoor tortoise enclosure. Here is a link to a page with a pretty goos and easily adaptable greenhouse version.
http://www.peakprosperity.com/wsidblog/81753/building-cattle-panel-pallet-greenhouse
http://www.peakprosperity.com/wsidblog/81753/building-cattle-panel-pallet-greenhouse