What do you want to coat? Film or paper?? As width goes up, paper coating by this method becomes more difficult. At a given width, about 16" or wider, it is easier to move the paper than the blade. With film, that is not a real problem as you see from Jim Browning's web site. So, to date, the widest that I coat is 16" for 16x20 paper and I only have one of those blades. It would cost nearly $2000 but I have not costed it out so don't count on that price. You see, when you cut stainless bar stock, it warps and bends which means that the material has to be straightened and then polished to get the 0.001" tolerance that I need. This just about doubles the price as length goes up.
Also, the 16" blade weighs about 1.4 kilos, so a 36" blade would probably weigh in at about 2.8 kg. Have fun with that! Wow.
And, a 4" blade is not 1/2 the cost of an 8" blade. The cost goes up in a non-linear fashion.
So, with this method, unless you automate it somehow, you are out of your mind!