This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
If there are a number of plates To be developed, place a rubber band, about 1/8 in. wide, around the ends of each plate and put them together in a tray. The bands keep the plates apart. The developer is made up as for a tank and poured over the plates, then another tray, or dark covering, is placed over the top. Allow this to stand, rocking the tray from time To time, the same length of time as is required for tank development. - Contributed by Earl R. Hastings, Corinth, Vermont.