Harvesting worm castings in a single worm bin
If you make your own compost bin by using a little died bin, putting holes in it for aeration, and a tap for taking off the juice or leachate. , it seems to me you do not then get the opportunity to take out the worm castings. Am I correct?
I am assuming that is why you otherwise use a commercial worm farm that has several trays which you rotate, taking the first tray off for its castings.