I made a couple from OSB board. You can buy it at stores like Home Depot, Rona and Revy where they sell lumber. It comes in 4' by 8' sheets, wasn't too expensive about $8 a sheet and most places will cut it for you. They cut it 3' by 6' and then the 2' square piece from the end I made a smaller one. I did the same as Cheryl in the last post. A layer of cotton batt and cotton canvas, stapled on the back. I didn't cover the back with felt, I just covered the stapled edges with some duct tape. When the top gets yucky from glue and starch etc, I can easily undo the staples and put a new canvas top on. After you have it all stapled, use a spray bottle and spray the top with water to soak it and then leave it to dry. The cotton in the batt and canvas will shrink and tighten right up to your board.
Since I have used these, I don't think I've even touched my regular ironing board. I really prefer the harder surface now for pressing. They are really easy to make, give it a try and I bet you use it more than your regular one too.