Ripstop nylon, lined with a fairly robust fleece, is what we had for our whippets. The edges were bound and a strip of twill tape covered the back seam too. If you make one with a fold over collar, you can put a slot in there for the lead to go through which means the collar isn't pushed out of the way and is more effective, folded back or right up round the dog's ears on cold or wet days. The other thing to consider, especially if you have a male, is the exact width and placing of the belt that goes round the body. You may need to taper the belt appropriately to make a comfortable fit. Or make long ties from twill tape which will fit round and knot on the dog's back, less elegant than a belt and velcro or strap, but perfectly effective.