The last piece, the doors, has to be on the barrel at the top and inside the barrel at the bottom. Don't forget to clip each piece in-between the screws. Will make it easier to screw the middle of each pieces. Works great so far. I figure we have to transfer the compost to the other side to cure at some point and start anew on the + side. Need to read more on the subject or watch videos. Hope to have enough for my garden next year!!!