I rough up the sides of a 2 litre icecream container with fine sandpaper. Put porridge and a tablespoon of sugar in a coffee grinder, add a little water and cook in the microwave into a very thick goo. Spread over the bottom of the container with a wet spoon, sprinkle yeast and add microworm from previous culture and in a few days they are all over the place. Lasts a couple of months and I have 4 on the go always.