Postage stamps are great for folding and making cards. Perfect size. Perfectly identical.
Here is one by Rita featuring an Australian tropical fish stamp.
This style of card decoration originates from origami. Then, from what I can gather, The Netherlands seems to be the place where the craft became huge using the outer cover of tea bags.
The funny thing is that even if you are using postage stamps, it is still called "Tea Bag Folding".
There are SO many different ways to fold and create. Just google search 'tea bag folding' and you will have plenty to be inspired by.
In comparison to Rita's card, which I find really classy, many on the web look a bit gaudy, but it is a matter or personal taste and trends in different areas.
Here is a basic little website. It's not that flash but starts with teaching the most basic tea bag fold to get you started.
If anyone knows of a better website with instructions, please let me know in the comments. (Elly?)