You've seen this type of rubber used in manufacturing mouse pads, dry wall sanding pads, and shoe insoles to name a few. For cutting 1/4 inch thick EPDM foam rubber; what would be the best kind of scissors?
Last time I had to cut something similar I used a pair of tinsnips, rather than scissors! Worked fine!
If I was only cutting 1/4 inch I’d probably prefer a straight edge and sharp scalpel. Here in the U.K. we can get a thing called a “Major” scalpel, which is heavier then the normal surgical type, and perfect for this sort of thing!
More expensive than some, but heavy 10/10 steel, are a lifetime ownership tool you won't mind paying to have resharpened some day. Every time I see mine I smile and think of Crocodile Dundee saying "That's not a knife..."