I bought some iron-on jewels and studs and decided to give them a try on these childrens caps. You have to put your iron on the hottest cotton setting and I didn't know if it would affect the caps or not. I turned the cap inside out and tested the iron on the cap and to my surprise it didn't hurt the cap. The iron-ons had about 5 rows of jewels and studs, so I cut off what section I wanted to use. I peeled the back side off and the front has a clear sheet that the jewels and studs stick to. First I placed the studs in the location I wanted them, turned the fabic over and then I followed the instructions that came with the studs. After I had ironed the studs on I set it aside to cool for 3 minutes. When I peeled the clear plastic off, one of the studs wanted to peel off with it, so I finished pulling the clear sheet off and then I ironed it for 10 more second. I had no problem with the jewels but went ahead and ironed it for 10 more seconds anyway. I think they turned out so cute and I'm ready to do more. The instructions do say hand wash and lay flat to dry, so I will probably stick to crafts rather then childrens clothes.