It depends what material the plate is made of.
There is steel diamond plate and aluminum diamond plate.
Steel obviously is harder to bend & cut.
I have a 3'x4' sheet of aluminum diamond plate, that i hack up and do stuff with.
Its really easy to cut. "If" you have a good pair of snips, and "if" you have strong muscle type arms you can cut threw it.
But any metal cutting tool will work on aluminum.
Ive used, Sawzall, Die Grinder with cutoff, Dremel with metal rotozip bit, snips.. Its easy