Okay, I tried a few things.
I cut the cut off the head from the tail, then cut the 'legs' between the two parts off. After filing the ends more-or-less-flat, I drilled a 1/8" hole in each, threaded some string, tied a knot and sealed it with hot glue. i put a piece of McM felt on the face so it would be safer firing out the barrel.
Eh. The biggest problem is that they aren't a super-snug fit in PVC, so the head slides somewhat freely while the tail is tighter. It doesn't splay out as nicely as Buffy's rounds. At 30-40', it's only ~1' apart out of the ~2' of string.
I cut the head off the tail, then filed it flat-ish. I drilled a 1/8" hole through the face, then injected a small amount of hot glue through the hole to form a 'bead' on the other side and improve retention. I smeared a small amount of hot glue on the face, then applied a piece of McM felt.
It's okay. I fired it out of an SVT4B into my palm. Stung, but not nearly as much as a standard glue-dome. This plastic does give, and a lot more than hot glue. It goes 50' or so. I only had time to fire it a few times, so I can't report these as the 'final' and 'official' ranges.
Fugly is a feature.