I was just doing keyword searches on here because I plan to make one soon and was debating using the silver stuff I have or canvas. I found this thread (and many others) that might be helpful to you. (I've decided to use 1/2" board that I already have, 1 layer of Warm & Natural, silver heat-reflective fabric then a removable pre-washed canvas fabric so I can wash it.)
Making Your Own Ironing Board--Did you use canvas or silver ironing fabric?