Here's some pictures of me putting together my springtail cultures:
Hardwood charcoal. Crush to smaller sizes (more surface area), great excuse to have fun with a hammer.
Boiling the charcoal.
Straining off most of the water and quick rinsing any charcoal dust off.
Then all you need is a ziplock and some springtails!
I like to keep an amount of water in the tupperwares and at least bottom of my cultures so they never come close to actually drying out.