I considered using broom handles for racks but decided to use 70x35mm timber instead, more solid. The materials cost $82 from Bunnings, which was less than broom handles. The studs in the wall were 500mm centres, and the racks are 1500mm apart on wall. The timber in each rack is 800mm long, with 710mm width usable. The rack spacings are multiples of 100mm.