complex equipment. The only hardware needed here is an electric drill, which most of us should have already. If the drill is in a drill press, so much the better - but it is not absolutely necessary.
Start with a block of balsa slightly bigger than the spinner

you will do is snap the blade and send it flying across the room. Coarse sandpaper is a much better tool for this job. Don't remove any more wood than necessary, this is not

design. Square all the edges, and draw a couple of diagonals on the end grain to find the exact centre.  Drill out a 1/4" hole in the centre (assuming an Aeronaut prop adapter), make sure you go at least halfway through the block. Knock off the corners to make an octagonal cross section,

meant to be a hollow block.
When you are satisfied that your prop adapter (with nut and washer) will fit inside the spinner, remove the hardwood dowel and replace it with balsa. Or, if you prefer, just cut the dowel off and glue it into place permanently.

The primary function of the backplate is to stop the motor shaft bending when the prop hits the ground, so it needs to be rigid. 1/8" ply is probably better than 1/16" ply. Mark out a circle, drill the centre hole to suit your prop adapter, and cut the backplate slightly oversize. Mount it in your drill, and smooth down the edges with a file or coarse sanding block.
Okay, now for the tricky part. Mount the prop on the adapter, with the backplate behind it, and offer up your balsa spinner. Mark where the prop blades touch the balsa, and cut a small notch. Offer it up again, and cut another notch. I use a half round file, it matches the curve of the prop blade quite closely. When everything fits snugly, and the spinner is sitting flush with the backplate, give yourself

and glue a piece of 1/4" hardwood dowel into the hole. Don't smother it with epoxy, just spot glue it with a dab

of balsa cement so the dowel can be removed later.
You need to remove a bit more wood in the centre, to allow for the prop nut and washer. Do this by hand if you enjoy carving, or simply use the drill press with a larger bit if you have one. Otherwise, drill the 1/4" hole right through the block and out the other end (it would be easier to do this right at the start if you want to use this approach). Replace the dowel from the front this time, only going halfway through and again fix it with a spot of balsa cement. When dry, return it to the drill and remove a portion of balsa to suit the prop nut. BE CAREFUL! Don't just jab your knife into a whirling block of balsa, all

a pat on the back - that was the worst bit!
On the rear face of the backplate, mark two holes for the spinner mounting screws. Hold the spinner in place (tape it if necessary), and drill these out. Now remove the prop,
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