if i sterilize the substrate, can i brake up a cake and put it on the substrate then put a layer of potting soil to keep the air out?

Or should i grid up a cake and put it in a needle?

Hey kid, my first terrarium I made from a lunch box and plate of glass I salvaged from an accident. The economy has got much better. enjoy it. Buy yourself lab equipment and grow crazy giant sized caps with nutrient misted, mycelium infested, car washing sponge cakes.

however, i got the secret medium for subtrateless medium...

but i wont share...