The endcap is a detail of typical JSR epoxy construction, the end is sealed with a disc of foam cut from a meat tray, over which a roughly 10mm thick layer of epoxy is poured. I added wood screws all around the casting for added strength and adhesion. Ignition is by piezo hacked from a cigarette lighter, I cast a housing using wire wrapped around a foil cup as a contact, in order to make it removable. The second bolt is there to cover a port for fuelling (butane from a lighter refill canister metered with a syringe) and venting.
Test results and damage pics/frustrated rants about another failed project to follow in a few days

edit: It works

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