Very nice build in one of my favorite subjects Torpedo Boats!!!
For Helices in a small scale I would use a short length of brass tubing to cut the pales (forgive me) out of plastic card sheet, (0.5mm, or possibly 1.0mm).
Camfer the end of the tubing to a sharp edge (a camfer outside works better). Place the sharpened end of the tubing on your plastic card sheet and and use a hammer to tap the other end of the tubing to cut out the pales, for as many as you need (a hard surface is best to put the plastic card on). You can use the same tubing to re-cut them if you want narrow pales by placing the tubing slightly off-center the cut-out pales and tapping the tubine with the hammer. With a little practice you will have a nice matching set to glue to a hub made of 3-3mm diameter plastic rod (I taper the end of the rod in a Drill motor, then file notches at an angle to the hub centerline in the hub for each pale to set the blade angle, and rotation direction (left or right). You may need to make a few hubs to get ones that are just right). Glue the pales to the hub with liquid plastic glue. THen coat with CA (wick-off the extra) fter they are completely dry. Cut the hub to length from the rod, paint them and glue them to your shafts. You might carefully drill a small hole in the end that fits to the shaft with a pin vice. Being careful and you won't break the pales off. Hope this helps.