The cardapult is a business card that transforms into a desktop catapult. It is powered by a small rubber band and is the thickness of 5 business cards. Check out the instructable for the how-to.
After seeing the business cards with gears a few months back (normal and planetary), I started thinking about what else could be made to fit in a business card. I wanted something unique and memorable that could represent me and my creativity and this is what I came up with.
I first got a blank card and sketched out where I wanted each of the components. I had some ideas of how it would be arranged, but I also designed a lot of stuff as I went along. Then I drew up the design in Alibre Express. I printed it out and cut everything by hand with a hobby knife. Cutting the parts out was a lot of work and not really practical if I wanted to actually give these things out. Initially I was considering trying to make my own dies to speed up the process, but when I ran across the Quickutz Silhouette for only $100 I couldn't resist getting a new toy.
After playing with the prototype and while I was waiting for the Silhouette, a few design changes were made. First the axles were made bigger to make them standard hole punch size and improve the strength. This required changing the arm dimensions slightly to accommodate the larger axles. The top edge where the arm folds in was rounded because it was being hit by the arm and bent out of shape. The bottom corners were cut away so that the legs could be more easily extended, and a few other minor tweaks were made.
I'm pretty happy with the design, so you probably won't see any modifications. This was really a lot of fun to make and I have a few other designs that I would like to build, so you may see some more projects along these lines in the future.