Being retired gives me the time to research and play with a lot of different products. As a result I am always on the lookout for different and uncommon items. The other day I ran across the most unusual knife, the Cardsharp by Iain Sinclair. They call it a Credit Card Folding Knife. It is the size of a credit card when folded. It has a shard steel blade with a plastic handle when unfolded and is a approximately 5 ½ inches in length.
I have played with the knife and unfolded and folded it numerous times with no sign of ware. The manufacturer claims that the handle is made of polypropylene which has the unique feature which allows for infinite number of folds without the hinge cracking. The blade is made of surgical steel. It is not a knife that you could use for prying or very hard use, but it will cut effectively.
Folded the knife will fit in your wallet like a credit card. If you are building a survival kit in an Altoid they fit perfectly flat in the can. In a survival situation even if the handle failed the blade would still be of use.
I purchased the knife for $13 on E bay. Be careful to not buy them from companies located in China, I have been told they are making knock offs.
All together a fun little knife to play with and it could be quite useful carried in your wallet or small survival kit.