I collected a bunch of veggie scraps in the freezer and made a stock out of them yesterday. It was really easy, except for my burned hand. I grabbed the searingly hot handle of an empty pot not once, but twice. I'm crazy that way. I put my hand in water and that seemed to help. When I woke up this morning it was weirdly purple like a bruise, but it looks and feels fine now.
Anyway, I mostly kept the ends and peels of carrots, onions, leeks, and celery. I added some sage, rosemary, and thyme for a bit of extra flavor.
I melted two gallon bags of frozen vegetables and then added a dozen cups of water. I boiled it all for about an hour, stirring occasionally. I strained out the veg and tried to reduce the liquid in my wok, but I don't think it actually reduced much before I burned my hand and gave up with that.
I tried to do a second batch with the wilted veggies but I learned that the stock should not boil for more than an hour or it will get bitter.
I put the broth in ice cube trays and back into the freezer. Simple, easy, and a little dangerous. You should try it. Kitchen waste is basically free, so free broth for all!