I ended up with 5 liters of extra wort, from my smoked porter. So I decided to ferment them in 1 liter seltzer bottles. Result was fantastic. I was worried that the bottles would explode. No problem, they can hold a huge amount of pressure.
In four of them I relieved the pressure part way through fermenting, then retightned the lids on the fifth I did not. That one deformed, but did not burst.
Yesterday I sampled one that had been refrigerated overnight. I takes a while to relieve the pressure in the kitchen sink, but the beer was excellent.