In article ,
"A. Kesteloo" writes:
This company makes cast iron doors. They are for a barrel stoves / bbq but
should work on a brick pit as well.
http://www.vogelzang.com/Manuals/bk150eMnl.htm

I suspect you could also hit up wood-burning stove manufacturers
or dealers and just order doors. I'll be looking for these soon
as well. I've also thought about those cast chimney clean-out
door assemblies. I imagine you can get these in large sizes.

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- Kyle