Here is a simple emergency-tool for cutting safety belts and wounded people's clothes.
Step 1: Inventory
Nowadays we all have an app in smartphone that collects our discount cards so there's a lot of plastic that should not be wasted. I offer you to make a simple tool for cutting safety belts in car crashes, wounded people's clothes and shoelaces - all you need is three cards, office knife, double-sided tape or glue.
Step 2: Cutting Side Cards
So cut a line in a card - the angle doesn't matter I suppose, than put another card under it and cut the same line.
Step 3: Cutting Middle Card
This one would need the same line but also put a piece of blade on it and trace the outline of the blade - it's simple, because blade's shape is simple. Than just put the blade inside, that's it. Put this part between two cards you already have, glue it all together or use double-sided tape (as I did). And make the inlet opening wider because if you'll use it in an emergency situation it might be difficult to put a safety belt in.
Step 4: Try It
After you finish - try to cut something, just to test.