Just a quick note to point out, if you don't already have it figured, that if you form a box under the cage feet, there must be a flat plate between the 'box' and the floor, extending beyond the box, if you see what I mean.
If you don't have this, you risk getting pulled up by the scrutineers if you are going to compete in any MSA type event.
I'll trawl through the blue book and post up a link if I can find the relevant section.
Kim
Edit:
This is the bit in question
http://www.msauk.org/uploadedfiles/msa_ ... Safety.pdf
It's drawing # 18 right near the bottom. It's not very clear and shows a bolt in cage, but shows a requirement for a 'spreader' plate under the raised box section.