This is a updated version of the Ultimate Prop Launcher. This update makes it work.
Please check the original page to understand this one. :)
NOTE: You might have to “break in” the whole thing, sota wear out the various surfaces to smooth them out.
The “Shaft” part replaces “Gear3” in the original design.
The “NewLid” replaces the “Lid” in the original design.
optionally, you can just drill a hole in the old lid to fit the new shaft, this is what “Shaft guide” is for. You glue it to the bottom of the old lid to act as a well, guide, for the shaft. Probably better if you make the new lid though.
(I drilled a hole)
The author marked this model as their own original creation.