This is a portable greenhouse, good to start seeds or small vegetables (basil, parsley, salad, cilantro...). it's really fast and easy to built, and super economic and ecologic, I made mine all out of scraps and in little more than an hour.
Materials :
Big plastic can (white is better)
Transparent or semi transparent plastic sheet
4 screw with 4 nuts;
4 little piece of plywood about an inch by an inch;
a piece of bike inner-tube;
Duck tape
Tools :
Jigsaw
Power Drill