Thinking about this, many moons ago in a galaxy far removed from this one I had to slice about 1/2" off a massive stack of gauge plate which was 12" to 15" long and varied from 1mm thick to possibly 12mm thick, as I say this was a long time ago.
These were shim plates to pack a reactor vessel up so cost was no problem.
Somewhere ????????? I will have all the off cuts which are the full 12" to 15" ? length x 1/2" approx wide and various thickness's
Never used any of these and as part of the Mass Downsizing [TM] I can take a selection to Bristol in a few weeks if anyone wants any.
I will only be there on the Saturday so PM me for a mobile number. These will be free to anyone who wants them but please don't be greedy or at least pass them round. From memory it was oil hardening steel. I can check as some of the full strips never got cut and will be with the oddments if I can find a rope long enough to go round my waist and a pocket of breadcrumbs.