I've been meaning to learn how to raise mealworms for over a year now. Last summer, there was a drastic shortage of mealworms, and our wildlife clinic really had to scramble to feed all the baby birds that we were raising. Unfortunately, it takes several months to harvest your first mealworms, so it wouldn't have helped for me to start then, so I put it off.
I finally got around to starting my colony a couple of weeks ago. I read several articles on the Internet about how to do it, and will try and develop my own method.
I bought a three-drawer plastic cabinet from Walmart for $14. I am using old-fashioned oatmeal as the bedding. I put a layer of about an inch of oatmeal in a drawer with about 1/4 cup of worms from our wildlife hospital. I put a couple of baby carrots on top and covered it with two sheets of newspaper which don't quite go to the edge of the drawers. The article said to leave a couple of inches between the newspaper and the side of the drawer. When I peek inside, the worms are usually on top of the bedding just under the newspaper, and then go down while I watch.