This is a propeller launcher with a design inspired from a toy i had as a child. It works well to print all at once, but i have added separate files as well.

You need a string and a rubber band to assemble it.
Thread the string through the tiny hole on the launcher and then through the hole on the pulley, then fish it out and tie several knot on it to prevent it from passing back through the hole. Then wind about 50 cm of string on the pulley by turning the shaft with the propeller. Thread the string through the handle and tie several knots at this end as well.

Now you can add the rubber band by pushing it through the hole at the end of the shaft and tensioning over the hooks at the back of the launcher. If the string doesn't return easily it works to add a little bit of oil by pouring it into the top of the launcher.