I'm leaning towards the Everlasting case idea. I can meticulously turn a couple on my miniature lathe- if done right, a handful should last, well, forever. The stumbling block for me will be having a chamber reamer ground to accommodate the special case- I'm envisioning a thicker case than a .22LR with around 2grain Bullseye capacity max, case mouth reamed for a .225" 45 grain cast bullet to be a snug thumb seated fit, with a ledge for the base to rest upon. .225" throat, .224 barrel, perhaps a 1 1/2 degree included angle leade for heavier longer nosed bullets. A couple potential donor rifles stand ready to receive it- either a Martini Cadet or Stevens 44. The Stevens would be better adapted to breech seating if I want to get truly crazy with this.
A Pope-style de/re-capper would be tasty- a couple weekends in the shop could see that accomplished. A tiny powder dipper, once the best load is worked out, would round out the tools needed to manage the rifle. Slow shooting for sure, but what's time to a pig? Spend the day at the range with a cup of powder, box of primers, box of bullets, a single cartridge case, a loaf of bread, and thou beside me crying in the wilderness.
I guess I better work up a drawing and start looking for someone to make a chamber reamer. At the risk of putting the cart before the horse, I think in this instance I would be well advised to cut the chamber first and then turn the cases to be a snug custom fit.
Thinking some more about this, the Stevens 44 would be more conducive to a switch-barrel system due to its design, allowing me to employ Digital (Dangerous?) Dan's design in a package deal for added pleasure (insanity).
