Approximately 1/2 activated carbon, then add pieces, cover with about 1.5 inches of carbon. The large piece (ginko leaf) is about 2.5 inches, all other pieces about 1.5 to 1.75 inches. There is room for a couple more pieces...I just didn't have any more pieces prepped and well dried.
View of fiber box in kiln...ready for firing. I fire with an open top.