I did try leaving the apples out to dry after a day in the oven on a previous batch, but it didn't work worth a darn (they actually softened up because of the humidity), and I really need to get a quality dehydrator or to build a dehydrating cabinet.
I have a dehumidifier I bought to dry out the basement after Hurricane Irene which could be used to speed up the process, but you still need a safe heat source; Fred and I keep coming back to a free floating light bulb dangling from the top of the structure. We have yet to test what the temperature might be in an enclosed space. Then again, the dehumidifier does throw off a certain amount of heat, so that could possibly do double duty. If that works, I could see buying a bunch of large metal cooling racks, and tacking 1"x3" strips to the sides of the cabinet to rest the racks on. It would definitely be cheaper than a quality dehydrator and allow me to dry more food at a time.
Another option we're starting to mull is this construction of a dehydrator cabinet, assuming we can find this kind of a heating coil, and possibly a thermostat.
So here's the apples after a full day of dehydrating in the oven.
OK, so why aren't they in the oven? Well, Fred and I just did a quick whirlwind clean of the kitchen, and the oven is in the self cleaning mode. I figured it made sense to do it now since it's nice out and we can open all the doors and windows in the house to avoid the stench of the high heat burning everything off. So, I sacrificed the apple rings in favor of a clean oven.