Step 1: The Design
The original design I'd seen had each shelf supporting the next by using the flange bases (http://goo.gl/9HOiY). The only problem with this was that I'd need to do a lot of pole cutting and the height between the shelves would be forever fixed. If I changed the design so that the poles were at the edges of the shelves rather then between them, I could keep the poles as one long length and use the side mounting clamps (http://goo.gl/UcFBh) at whatever height the shelves needed to be. I also saw that double clamps were available (http://goo.gl/2DZVE), so by rejigging the design I could make one long shelving unit rather than three separate ones and share the mountings and pole between them.