Instead of building a steel fireplace in the greenhouse I should build two small brick kilns and alternate between them firing bricks and thick floor tiles for building projects. Heat the greenhouse/shop and not have to pour a fuck ton of concrete slab floors. The bricks won't be exposed to frost so I think 12 hour nightly firings would be sufficient. I need like 50k 12" floor tiles and I bet I could make all of em over ~5 winters. Would just need to mold 500 tiles a week, making a clay extruder and cutting the tiles with a wire might be worthwhile. Would be better than spending 75k on concrete and would look way better too.