Our old camp-stove toaster finally rusted out a few years ago, and I had been looking for something better - something that would give me a slice of Liz's delicious home-made bread toasted to a nice golden brown. At last I came up with a very simple solution.
Boy, does that look good...or what? There are two components to my toaster: underneath is one of those pan-warmers that you put under a pan to keep it from getting too hot. Then I bought a small round grill - this one is about 10" in diameter - a smaller one of 7-8" would be even better.
All it took to make the toaster was to weave two pieces of stiff wire, such as coat-hanger wire, through the grill and then bends the ends down at 90 degrees. The ends of the wire just fit into the holes in the warmer.
This side view shows the approximately 1" space between the warmer and the grate.
The grate and the warmer are each flat and easily stowable. I've been very pleased with this - it toasts much more evenly than the upright commercial versions.