J. Phil Thien's Projects

Does the "drum" the Thien separator sits on top of have to be circular in shape or can it be a rectangular box with a circular opening on top to fit the baffle? I think I understand the concept of how the separator works, basically circulates the air and chips so they are not sucked in through the center outlet but instead fall through the baffle. Once the chips fall through the baffle does it matter that the catch "drum" isn't circular? Maybe makes it less efficient? The reason I'm asking is it's hard to find the correct size drum for the space I'm trying to use for the separator. It would be much easier for me to build a rectangular box to custom fit the space. Thanks!