I did follow the advice given by someone earlier on the board about this topic. I bought a piece of wool padding (intended for rugs) and couldn’t be happier. I just ironed 512 small pieces (HSTs) and it totally flattened them. I used steam. The only thing I noticed is that I could smell the “wool smell” the process produced. However, I ironed the next step of the quilt (strips of HSTs), and again, it was flatter than anything I have done. I will put up with a slight smell that doesn’t stay on the fabric and disappears soon after I am done ironing for those kinds of results. Get the mat!!!!