At first you must have an old furnace which is heated up with wood or other material that provides nice and natural heat source.
Here´s mine:


In the other room i have a heat wall which is heated up during the burning
process:


Raw amanitas are wrapped to a newspaper and put into a space in the heat wall and left there overnight. Circulation of air and enough amount of heat provides far more better conditions than electric oven.
Here´s my final product, dried amanita muscaria powder:

Personally i think that if you have an old house with a furnace and a heat wall there´s no point of using the electric
oven cause in my experience it takes a lot of time and wastes too much electricity. Those old heat walls are also safe way to go because the temperature in those should be just about right to dry the raw material rather than killing active ingredients.