Ok Curt,
Ah yes, working in the warm sunshine, so much more pleasant than being stuck inside a greasy shop. I've got to wait another five or six months before that happens again....sigh...Anyhow, I hope the following gives you something to work with.
I made the furls 'A' & 'B' out of brass. In this case 1.250".
The ID is just enough to slip snugly over the handlebar. I glued mine in place with clear Automotive Goop, but they could be locked in place with small grub screws too.
After that I gave them some substance by wrapping a length of truck inner tube along the whole length, beginning at the narrow section of furl 'A' ... this was also glued down along the entire length and held in place on each end with a small amount of electrical tape. Then the end was carefully trimmed with a very sharp utility knife. After that, I wrapped the rubber with cloth hockey tape (I think canvas webbing would work nicely too), starting at furl 'A' and working my way to the handlebar end and once again trimming the end. The ID of the end cap 'B' was machined to fit over the OD of the tape at the handlebar end and after liberally smearing it with Goop it was fitted over the taped end and locked into its final resting place with the wedge bolts (getting the tape to fit into the end furl can be a bit tricky). The locking wedges themselves are just made out of bits of scrap aluminum I had laying around and machined (poorly) to fit loosely inside the handlebar. I gave the whole taped section a couple of coats of clear lacquer to keep everything locked in place and to take that icky-sticky feel of the hockey tape away.
The dimensions in the drawing represent what I used and are included only as a suggestion and of course could be modified in just about any way to suit...this sort of grip can also be adapted to twist grips...of course you must rely on glue alone to hold the end cap in place and build up the other bar to match the diameter of the twist grip barrel.