Used Kamado with no firebox

Hello all,

This weekend I picked up an old kamado cooker off of Craigslist for $40. It's in great shape with just a few hairline cracks in the dome. I'll take it apart and fix them with JB weld.

My biggest problem is that it has no fire box. Does anyone have any suggestions on what to use or where to get one without spending an arm and a leg?

It looks identical to the one in this thread.

http://www.bbq-brethren.com/forum/showthread.php?t=44688

If you click on the link in the post I made it is the 5th picture from the top. That one is in pieces, mine is missing.