Re: Alcohol stoves in use?
I bought an origo 3000 at a swap meet and it didn't come with the gaskets either. Rather than buying them for $16 each plus shipping I got a piece of rubber from mcmaster with some other stuff and cut my own.
I found online that they are supposed to be 92 mm in diameter. This just covers the raised part around the grate like skygazer said. Unfortunately I didn't know the thickness and guessed. I got 1/32" thick Buna-N rubber, shore 40A hardness. 40A is described as the hardness of a pencil eraser.
While the gaskets initially worked ok, they seem to wrinkle and then stop sealing. I'm not sure if they are just too thin or if the buna-N can't stand up to the alcohol. The underside of the gasket gets all wet with condensed alcohol. It's supposed to have good alcohol resistance, but maybe something else would be better.
Has anyone tried bicycle tubes? Those are butyl rubber.
I did manage to also use a bit of the rubber to seal the inflation adapter for my dinghy into the hose for the pump. I have about a dozen different sized ends for the hose but none are the right size. So even if the gaskets don't work I still got something for the $6. And I still have most of the sheet left. I think it would work well glued to the bottom of stuff to keep it from sliding so easily on boat tables and counters. And dampen hatch vibrations.