I use a June Taylor ironing pad (rectangle 20"x60")that is made for their custom large ironing surfaces. I just put it on a piece of plywood. I just Google it and I guess they don't make them anymore.

I put a piece of plywood 2' x 4' on the top of my ironing board and used lock washers and screws to hold it on. (I don't iron anything except fabric) I covered this with batting and some silver colored fabric, that some ironing board covers are made of. I believe I have 2 layers of batting. I stapled this to the underside of the board and I love that I can iron fabric selvage to selvage without moving the fabric. Another friend of mine does iron so she has some 1 x 2's under the board that are spaced the width of the board itself.....she can remove the board when necessary and use the original board.

Sharon Schamber recommends a harder surface for quilting. She has several Youtube videos where she shows how to make your own pressing surface. My dh made a plywood platform for my ironing board so I have a larger surface to press (love it!). We covered the plywood with a layer of Warm and Natural batting and a layer of duck cloth over that. Works great. Here is a link to one of Sharon Schamber's videos:
https://www.youtube.com/watch?v=4LGbXou_u4c