Sounds like a cool idea, but there isn't a standard small arms cartridge case large enough. Your target of 3 Tbsp is ~45mL of oil, which is equivalent to ~694grn H2O case capacity. For perspective, a .50 BMG case is only 293grn H2O capacity.

You'd have to look into something like a 20x110mm cartridge, as I think that would put you in the right ballpark for 3 Tbsp, maybe even a bit larger.

Throw 8 20mm cases on a menora and you'll certainly have a conversation piece!