I have not worked with PF agar but I did use Malt Extract Agar to grow mushroom mycelium from a mushroom cutting. From there you can place it in a growing medium like washed wild bird seed or brown rice flour. Its pretty amazing how quickly it grows and yeah I would get contamination sometimes.. Usually trichoderma as my clean air box consisted of a plastic storage container with glove cut outs. I would spray my gloves with lysol and clean the inside and out after use but after about 15 or so uses it would consistantly grow trichoderma so I had to toss it.