You can only use one block to strut your stuff.
I wanted to make a sample of how you can recycle and make some great cards in doing so for the Die Cut Divas on flickr. We're having a challenge there, so please come join the June challenge.
I also wanted to enter a challenge at Less is More. I hope my card is "less" enough. Here's my card. I made the flower from tissue boxes and cut the corner square from a corrugated lotion bottle protector sleeve. It's ok to use a rectangular card. I think square is more striking, myself and maybe I'll use a square card next time.
I'll show you some of the other cards I made also. The first one below is for my son and his wife's anniversary later this month. The sexy nylons are from her packaging.
Have fun and recycle, re-purpose!