That's your challenge, and to do it right, you'll need to give then a stock piece of Mana (rack or Soundstage, etc) and let them copy it *identically*, including how the corners are welded, so you end up with the *exact* same item, only constructed from non-magnetic (make sure it is, as some SS is magnetic) stainless steel. And that includes the spikes/nuts.
I used a fabricator in Wrexham (not sure if they're still there), but there are bound to be a few near you. Also, in terms of identically replicating, the same applies with the glass shelves, so you'll need an original piece of glass to copy, especially to remove the 'tuning strips' from it (therefore try and find as many as you can), so that the glass resonates at the correct frequency, when 'tuning' the shelves with the spikes.
I can measure mine and let you know the dimensions, if required.
The boards are simply MDF, but make sure that they're cut to the exact size and thickness of the originals, and that you have them laminated (as per the originals), to minimise spike sinkage. After that, it's all down to the set-up, which unfortunately in order to optimise is a bit of a black art!
Good luck and let us know how you get on
Marco.