It's cheap. Clay ovens can be free if you're savvy with finding or digging up your material, and it will likely cost under $400 even if you’re buying all your material. At this low cost, there’s hardly a reason not to build a clay oven. You can knock it down in a year and still feel like you made it worth it. You can build a second one that’s better than the first. And maybe a third!
Play with mud! Let the clay squish between your toes. Squeeze it between your fingers. That’s what building a clay oven feels like. You’re five again and playing with mud. What more do I need to say?
Natural materials. Clay, sand, firebrick (made from densely fired clay), maybe sawdust, maybe glass bottles, perhaps some cow manure or straw. All the materials we build with are natural. They decompose or can be recycled. No hazmat suit necessary! Kids are invited!