Choose a foil pan size the best suits you. From small to large sized pans all work well for this technique. It is very easy to do and easy to control. Break up colonized substrate in your foil pan after wiping it down with alcohol really well. Break up your colonized cakes into the bottom of the foil pan. Break them up into small pieces with an estimated diameter of 1/4" - 1/2" inch. This will leave a more concentrated and compressed mycelium block. Cover your broken up mycelium chunks with 1/4 - 1" of pasteurized or sterilized 50/50+ mixture with the proper moisture level. Moist enough to the touch but not dripping when squeezed. The top level of your casing substrate must be all the way to the top of the foil container so that there leaves little to no gap between the top 50/50+ casing mix and the foil that will cover the top of the foil container. Put the foil tightly around the edges and place it in a clean dark location at about 75-80 F degrees.
It might take a few weeks for it to be ready. Check it by opening the foil on top to view it after the first week or so to make sure there are no contams. After that check it every 2-3 days leaving undisturbed mostly. When spots of mycelium begin popping up on the casing layer usually what you would want to do is cover these first spots up with some more casing soil to allow for an even colonization of the top casing layer, an even pinning, and to prevent overlay, but in this case it is not necessary to cover these spots. When about 3/4th of the top casing layer is thickly colonized, it is now almost time to flip the pancake into a bigger sized foil container or bin if you wish. First, you must pull the sides of the foil pan to expose the side of the colonized block. Pour some mineral water with a sterile or boiled concentrated hydrated lime mixture into the side of the container flooding the block about half way up the sides. Allow to soak for 24 hours and then dump out the exess water and proceeed.
Lay down some vermiculite soaked in peroxide on the bottom of the new bigger foil container. Make sure there are no puddles of peroxide in the container, just what the vermiculite can absorb without dripping. Flip the colonized "pancake" onto the middle of the bigger foil container and sprinkle some dry vermiculite on top of the "pancake" covering almost all the top surface and mist generously with a pump style fine mist sprayer.
Cover the foil tray with another foil tray the same size as the bigger pan by placing it upside down on top of the one containing the "pancake." This will create moisture and a good temporary growing environment. Mist regularly 2-3 times daily including the top of the upside down foil pan covering it and place in a shady cool place either indoors or outdoors. Within a couple of weeks of a cool humid environment you should begin to see tiny pins which will shortly develop into larger and larger fruits.
You can transfer the pan into a bigger growing container after the mushrooms outgrow the top of the upside down pan covering it to allow the mushrooms to grow larger.
All kinds of foil pan sizes work.
If you don't want to flip them you can use them as foil pan casings as well. Using them as casings also works well but it takes a bit longer then the pancake tek and requires a lot more care. If using them as casings you want to cover up the mycelium that first shows up up with some more sterilized or pasteurized casing soil leaving a fluffy layer of casing soil on top covering it up and then cover the pan up again with the foil cover until you get an even colonization of at least 3/4 of the top of the casing layer and place it in a growing container with some perlite on the bottom.
You will want frequent air exchanges, plenty of indirect light and a humidity of about 85%. It might take up to 2 weeks for pining depending on many factors including environmental conditions. Mist twice daily or as needed.
Here's 3 of the same size containers using the pancake method with vermiculite on top. Same thing, you wait until 3/4 of the top casing layer is colonized without worrying about overlay. Then flip unto a bigger container with peroxided vermiculite on bottom. In this case 3 were placed together in a big foil container and the container was then placed in a bigger bin with humid perlite on bottom. The top of the pancakes is now very thinly covered with dry vermiculite and it is misted very generously. Mist regularly after that 2-4 times a day.
Different sized pancake patties. A contam had to be cut out of this pattie. If you encounter contaminants the pancake tk is the best way to go to help control contaminants. However, always cut out contaminants as soon as you can spot them and spray the region with pure 3% peroxide.