That part i figured out
the problem is , the WB would be 'free' to move. Need some rentention mechanism...
I imagine adding (soldering..) 2 copper foils around the WB, so their size would match the HDs, and drilling holes around the upper foil so it can be screwed to the upper HD and the lower foil would make contact with the lower HD.
Still, this would cost the same price as buying a the real thing from DTek...