Essentially a lawnmower flipped on its side, take blades off and coil rope, when you start the mower and engage the engine it will spin and coil up the rope.
keep lawnmower body on or off depending on ur style
A few tutorials out there on the interweb..I think most use a honda gx engine. Be prepared to spend some dough tho, build+parts+maintenance...is the roi really worth it?