Paper airplane (and other things) launcher

Recreated https://www.printables.com/model/858661-one-piece-paper-airplane-launcher in FreeCAD due to source design files not being available. Replaced the airplane holder part with a block with holes to attach other things.

Included a simple slot for paper airplanes and pins to attach it. It's kind of a pain to get the pins in but I managed eventually. 

Eventually I might make a new holder with part of it cut out to make the pins easier to access. It's not necessary to pin every hole, I just pinned two. 

Since the FreeCAD files are now included here you can use them to design other attachments to launch other things and/or easily modify the mechanism itself e.g. to make the springs thicker or add more of them.