Hello Mike!
Unfortunately, the size of your desired worm casting bed would be incredibly difficult to build if you’re looking to have the castings fall into another container. A more simple method that can accommodate the size of your bed would be to make a simple raised bed and fill it with a mixture of newspaper, peat moss, compost and other organic materials for the bedding.
As far as food goes, dried manure, table scraps, garden waste, coffee grounds, and crushed fine crushed eggshells will do just fine. It is recommended that you bury your scraps to help with any unpleasant odors the food may put off. Be sure to avoid foods such as meats, processed foods, citrus, or any foods containing fats/oils.
You’ll begin to notice the progress after a few weeks and once you are satisfied with the results, place scraps on one corner of the bed to lure them away so you can harvest your fresh worm castings. Remember that once your worms are up to full speed, they can eat their weight in food in a single day. Be sure to replace diminishing food as they munch through to keep your worm farm happy!
Check out our page for more details on worm castings and products that may assist you with your new bed!
https://www.planetnatural.com/worm-composting/
Hope it helps!