Materials for top-bar hives
I read in BfD Journal 67 about the Gorongosa hive in Mozambique. This reminded me of the top-bar hives I made from four heavy sticks (two long, two short) that formed a rectangle. I wove split willows to form a half cylinder under the sticks. I left a hole at one end and coated the inside with straw soaked in wet clay slip. I put top-bars across the top and bees in the hives. I thought the clay soaked straw might move up with the combs which would mean mud in the honey. The bees however propolised the mud giving it the feeling of a hard surface, almost like ceramic and this prevented the straw coming up with the combs. The materials for these hives cost me nothing and the bees did well in them, and to my knowledge are doing so still.
I also made top-bar hives from stone and adobe, which is soil moistened with water, with chopped straw or other fibres added for strength, then allowed to dry to the desired shape. (The best adobe soil contains 15-30% clay to bind the materials together, with the rest being sand or larger aggregate.)
Plastic 55 gallon (250 litre) barrels can be cut in half long ways to make two half cylinder hives from one barrel. I get the barrels from a local dairy. I was unsure if the bees would do well in these hives yet they have been occupying them for ten years!
Important Check what has been stored in any barrels you use. If they have contained insecticides they must not be used.