I was super-excited about Vortex when it came out, and did quite a bit of experimenting in the area. I haven't had the time or desire to continue experimenting lately, but here is what I did do:
I forget which it is, but either 1 1/4", 1 1/2", or 1" PVC pipe is nearly a dead-ringer for the size of the discs as-is. If you're fine flinging plastic rings at each other, they might work in stock launchers; I think that I had a problem getting mine to fire, but it might have been that I wasn't depressing the disc-detector. Frankly, since the discs are slower and there isn't much to get stabbed by, I'm fine with them unpadded as long as they're finished well (deburred, sanded).
You could also just theoretically take standard pvc pipe insulator, and glue it on instead of having to mess around with craft foam, and then do what you said, with the bumper pad on top.
1/2" Pipe with 1/2" pipe foam is just slightly
the wrong size to fit in a stock blaster. The PVC ring doesn't catch on the throwing arm inside the blaster, it just tears through the foam. That doesn't mean that this style of homemade discs are out of the question, but it does mean that we either need a different method or they're only useful for homemade launchers.
In every case, all the top padding is needed for is to activate the disc-detector lock. Rings fly just fine by themselves.
As for blasters, I made a test-rig to launch the rings, but didn't have the equipment here to really make it work. What I did is basically make a catapult with a track on top, no springs required.