I made my daughter a sailboat top, and thought I had just about nailed those buttons down. I sewed them on by machine, using double the number of stitches the guide calls for, then went back over that and sewed them down by hand, because my kid is a chewer. It seemed she had barely dragged them over her lips before I was pulling a perfectly chokeable button out of her mouth, to great protest. Should I just go for snaps till she outgrows her unnatural appetite for plastic? I was using regular cotton thread. Would synthetic be stronger?