Note that the end of the metal shaft is bent back about 1/8 inch to form a retainer barb that keeps the propeller shaft in the tubing. Pliers with one slim round jaw work well. Make the retainer barb with a rough end, and larger than the ID of the tubing, so the tubing will stretch over the barb and then close around it for maximum retention.
I have caught many fish with proptail flies: steelhead, 3 species of salmon, char, bass, freshwater dorado, as well as many saltwater species—barracuda, jacks, tarpon, snook and even triggerfish. However, the metal props are heavy (about 7 grains for larger props), making the flies tail-heavy and harder to cast. Plastic props are much lighter, and will not cut through a flexible mono shaft.
Plastic propellers can be made using two metal propellers and strips of that obnoxious plastic that is used to package most modern electronics—the clear plastic that needs a mat knife and a lot of swearwords to open. Cut a rectangle of this stuff a little larger than a metal propeller; sandwich the plastic between two metal propellers, grabbing the sandwich off-center using a pair of pliers (the sandwich will gape quite a bit at the other side because the propellers are angled and swept back, whereas the plastic is flat). Dunk the sandwich in boiling water for a few seconds, squeezing the pliers so the plastic deforms somewhat toward the shape of the metal. Then grab the sandwich at the center—making sure the two props are still in alignment—dunk the sandwich in boiling water and squeeze hard. Quench with a brief dip in cold water. If done properly, the plastic will closely conform to the angles of the blades, and the raised “hub” of the blades will make a dimple in the plastic. Trim the edges of the plastic to the shape of the metal props (I trace around the metal with a Sharpie first) and don’t worry if the trimming is not exact; leave extra material around the hub area for more strength (you can glue on a sequin for even more strength). Poke a hole in the center of the hub with a pushpin. To attach the plastic propeller, I use the PBL and bent pin method, but a 30lb mono shaft will do. SoftGlass, a material similar to PBL but with 20% larger diameter, works well for larger flies. As in all propeller flies, the dressing must be short enough not to interfere with the prop, and weeds, filamentary algae and the like will also inhibit the prop.
Flies with plastic propellers look good in my test tank; they have been eaten by many salmon, as well as by dorado and tarpon, and I welcome anyone using these plastic proptail flies for other fish and sharing their results.