This is recreation of a Roman ballista. Its small (obviously), and isn't an exact replica (Romans didn't work in plastic). Its about the right size to fire a pencil.It should be fairly obvious how it works, but I have some instructions below, and a short movie.P.S. I am aware of the Thingiverse policy not to publish "weapons". I see this as a toy -- it can fire a pencil about two feet with considerably less force than I can throw it. However, please be careful as points can always put out eyes. Also I know someone could potentially beef this up until it fires knives at a 100 miles and hour. Please don't.TODO: this is a work in progress because there's some things I want to add. -- a mounting point so you can put it on a "table" (a stand on a pedestal). -- a ratchet, winch and trigger mechanism, that are vaguely period(1) Print out the parts: 1 of each of the body parts (technically these should be called the ladder) 1 pair of arms 2 frames 2 pairs of winders Clean the pieces up, and maybe smooth the bore of the body parts a bit.(2) Assemble: see pictures for some help if needed.Now you are done.