Oh well.That was a very nice way to say, "Go buy one".
Still, I fear that would require some effort.
I'm going to mark this one as a pie in the sky fantasy that will never get built.
Building an oven, even just a low temperature oven takes considerable time and work. Depending on what you want to toast there can be quite a bit involved. I worked with more ovens and heaters than I care to remember and my solutions often involved the phone on my desk and calling furnace, oven or heater people for solutions. It was more often than not more economical and feasible to buy than build, even for custom applications.
Ron