Features included are a hot plate, pre-heated air curtain to keep the glass clean, upper air inlet for secondary burning of gasses and a deflector plate which throws heat back into the chamber whilst also directing hot gasses past the underside of the hotplate. (That’s the theories anyway..)
As it stands it weighs in at around 64kg and apart from the Pyrex lid for the window and two metres of fire rope all material used was second hand and didn’t cost anything. Some bits have been in my garage for over seventeen years and the brass used for the door hinge bushes I’ve had since 1986, even then they were scrap parts from a damaged machine (how sad am I for remembering that

Anyway, it seems to work ok.