This device was developed by Albert Knight to enable two Apidea polystyrene hives to be fitted together so that a larger number of frames could be utilised. The dimensions that I have quoted in the drawing have been taken from an actual example that Albert made.
The rim pieces that are marked with a * should be pared down to fit the boxes concerned as both wear and dimensional variance between batches of Apideas will alter the 'fit'.
The example that Albert made was left untreated... I personally would be inclined to use petroleum jelly on the contacting surfaces and to treat all the other surfaces with linseed oil.