Such things exist but are incredibly expensive. For example, I can't remember where I saw it (some show I saw like 20 years ago), but some really expensive ind

Such things exist but are incredibly expensive. For example, I can't remember where I saw it (some show I saw like 20 years ago), but some really expensive industrial process has a vacuum sealed double walled vessel. Basically, a Hydroflask shaped like an oven. It had low thermal conductivity, but the hard part was keeping the thermal expansion from cracking it open.