I was planning on making several TBH swarm traps with the same width and depth of my TBH's and was wondering if any of you had any advice on how many bars it should be to make it big enough to be attractive yet small enough to be manageable.

My hives are Kenyan TBH with the available are for the bees as follows:
17 1/8 inches wide below the top bar
8 1/2 inches deep
6 5/8 wide at the bottom
With those dimensions one 1 1/4 top bar would give about 195 cubic inches of space. How many bars would be best to use to make it large enough but not too large. Thanks for the imput.