It is a very simple system that is based on the Joe Jenkins “Lovable Loo “. I’ve been using it for well over a decade now. I think I still have a copy of Joe’s book in digital form that I could probably share if anyone is interested.
I purchased a “privy kit (http://www.ecovita.net/privy501.html), built a wooden box and added a little 12v computer fan that runs on solar which causes it to be odorless while in use . That’s pretty much it.
Being the only one to use it, (my wife is still fecophobic), it takes me two weeks to fill it. I use a disc of newspaper and a lot of sawdust after each use. Sometimes I add powdered biochar to the sawdust. But that makes it a bit dusty. Alright for the man cave where I have mine, but probably too messy for in-house use.