[rcktscientist]

Alternative kiln idea:
Buy a Plug & Play PID ramp controller box for a 120v kiln ~$250
+ buy a ceramic thermal stove (for hot combs) ~$50
+ buy 1 sq. ft ceramic fiber blanket ~$20

$320 plus some time cutting the fiber blanket to create a 'door' and a little more time reading the manual and programming, then you can properly anneal marbles to your hearts content. That little oven probably holds at least 10 marbles. Perfect investment/cost/complexity for a hobbyist. Just be safe and smart with high temps and airborne blanket fibers.