Salt if you have an electric oven you can put it on the lowest setting and prop the door open.
I have dried tons of peppers like this.
A gas oven puts out moisture from the gas and doesn't do as well but I have used them for it.
The air conditioning in my house keeps the humidity down so in the summer and even now things dry out great.
With my electronics background I have no idea why I haven't built a killer dehydrator.
It would be so simple.
Worth