Like so many others, I started by buying a cheap pizza oven. The cheaper the better, because those are easier to modify. I currently have it (semi-)well insulated, and have it controllable by a rPi running Klipper. Great, now I just have to tune it.

Except that it's not heating quite a quickly as I'd like. I can't control both heating elements without a better heat sink on my SSR. I also have to have the door open a crack to get my thermocouple in there. Oh, and when I get to tuning the cooling phase I'm fairly certain I will need to open the door manually. Oh, and I hate the insulation job in general -- it's a weird shape, and much of it's vertical, making it more awkward.

WHY do I even need the pizza oven? Let's look at what it actually gets me:

1. Two ceramic heating elements.
2. A poorly made metal box.
3. A glass window.
4. Some admittedly nice looking trays I can slide PCBs in and out on.
5. Some decent wires.

Everything else gets thrown out or replaced. And there are some limitations inherent in some things like the metal box.

They make a special type of cement that goes around industrial furnaces. Rated up to 1200F (about 650C). Way above what I need. And it's moldable, has great structural strength. It's not insanely expensive, either. https://www.buyinsulationproductstore.com/calcium-silicate-1/ (This is the first result I found, not necessarily endorsing the company yet).

That got me thinking about making a mold for the inside of the "oven" and being able to run cable channels (pending: how to insulate the inherent hole created by a cable channel), mount internal fans (pending: can I reasonably get fans that operate in those temperatures?), maybe even create affordances for an eventual conveyor belt and...

Okay, I resisted making a project for the reflow oven because it was just like everyone elses. I'm still going to make that basic one -- I need to get some boards done -- but I have the makings of a "real" project if I start pouring concrete and adding conveyor belts.