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.
Obtain a tomato or other can, 5 or 6 in. long and i in. in diameter, which should be secured before it has been opened, says Camera Craft. Cut both ends exactly half way around, keeping close to the edge, as shown in the first sketch, and slit it lengthwise to open the side. Trim off the end pieces to within 1 in. of the center and cut off the surplus tin of the sides of the can, leaving enough to bend over and form the ends of the tank as shown in the second sketch.
The support, as shown in the last sketch, is made by screwing together three pieces of wood, the base piece being 6 1/2 in. square and thick enough to make the tank solid and heavy. Bend the sides of the can over the edges of the two uprights and tack them firmly to the sides, bending the tin so as to have a rounded surface that will not scratch the films. The ends of the can are bent over sharply to form the sides of the tank. Procure a round wood stick, the length of the tank, place in position, and fasten with a screw through the tin at both ends. Give the whole tank two coats of black as-phaltum varnish to protect it from the action of the developer.
Ill: For Developing Roll Films