Hey John, this is my first fatcutting. This was a piece of the trunk in which I had an airlayer above it, so after that one was removed, I cut this one.
this is how I did, as I wanted to save the skinny branches from it. the lenght was about 25" and the width of it is almost 2 1/2". I crumbled moist/ barely wet) newspaper and padded around the entire thing. I put a little rooting hormone at the basal 1/2". the crumbled paper around up to that area where the white powder was, so basal cut was exposed. I put it inside of a plastic cup, it was loosely inside the cup. I put the cup with the trunk laying down inside of a plastic tub and put it inside of a black garbage plastic bag- and in my cabinet over the heating vent. In a little over a week it had amazing roots all over. it is thriving now. the fat ones have a lot more energy and given the right warm and moist (not a lot), each 3 days or so, I opened and gave it a little spray, but did not open all the way... to my surprise it was my quickest and fastest rooting.
be sure it is very clean and have no fly eggs in it, so give it a good washing/soap and dry excess water before you put in chambers.
the pictures of it is in my posting named Black Friday Fat and Rooted... I could not repost the link for you to see.