Just a small one with one grill. I can get descent bricks for nothing so I want to give it a go. The problem is that the area I have ear marked to build it in is flagged and I'm not sure that they are that level. Would I need to make a concrete base or something to male a level base, or is there a simple way around it? It doesn't need to be anything much to look at. I'm all for practicality over esphetics.