Components for a new curved-vane spider:
1. a sawed-off portion of a PVC hex coupler
2. used-up (purol) hacksaw blades
3. some tiny machine screws
The hacksaw blades were courtesy of Ken, who must be using them up at a tremendous rate what with all the kiosks he's manufacturing.
After drilling small holes in the hex coupler, I bolted the hacksaw blades (via their existing holes) to the coupler using the tiny machine screws (I believe they are 3/32" screws, with matching nuts).
Then, a rather inefficient use of resources: I filled up the "gap" in the inside of the hex coupler with more than half a tube of epoxy putty (about $2 worth). Taking care to put a big-ass bolt, wrapped in masking tape, in the middle. That way I won't have to drill a big hole for the bolt of the secondary holder.
The finished assembly can be seen below. Nicely curved hacksaw blade vanes to reduce diffraction effects.