>>I feed out of bowls.. they don't empty them of food though thankfully.. They did at one point but gave up on it.. so now I don't go through quite so much. I feed them cheap dog food too.. (21% protein in the FMV brand $3.49 for 20#) plus I supplement that with cheap cereals (puffed rice, puffed wheat, etc) and sunflower seeds..And other goodies like leftover chicken.. veggies, fruits.. anything not quite fit for humans to eat anymore but still good for rats to eat...
I use a beer mug (a very heavy bottomed mug). The mug holds the food. It is about 5 inches deep. It is too deep for the rats to dig everything out and also too uncomfortable and too small for them to sleep in there. But if they want to eat, it isn't too deep for them to stick their head in there and take the food.
It is heavy enough so that, if done right, it does not tip over EVER!!!. The only time it has tipped over was when I had set it on uneven bedding. (ONLY ONE TIME!!!!)
It works pretty well. Even when the food gets to the bottom, the rats are still able to stick their heads into the mug deep enough to get to the food.
The only rats taht are small enough to sleep in there were the babies that were about 3 to 4 weeks old. It was really cute: they would bunch up 4 to 5 in a pile and sleep in there.
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If you haven't tried a heavy bottomed beer mug that you can buy at yard sales for 5 cents, why not give it a try? You might like it. Look for them at your local yard sale. Offer them 5 cents and more often than not, the vendor will be willing to part with the mugs. This is because I think that most people at yard sales just want to get rid of their junk. They really don't care about making money 
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Longtang. I like snakes and rats.