The sleep mask I have (though I seldom use it), I believe I got at Target or a supermarket - a soft silky material, and velcro fastener in back. It has the soft cushion at the bottom that others have mentioned.
I have a couple of the eye cushions with beads or seeds (I think some use flaxseeds?), but these don't have a headband so aren't suitable except for rest periods flat on my back. I think there's a benefit to having gentle pressure from the weight of the seeds on the eye area. The material is silky. However, I tend to put a facial tissue over it before putting it over my eyes, because it's a pain to wash those little eye pillows, and given the issues I have with my eyes, it's important to have anything touching them clean.
Urban, that's a creative idea to sew magnets into curtain hems! They must be powerful, to hold up light-blocking curtains. We have blinds on our bedroom window too - and it helped when I also put an overlay curtain over them. Actually, it's not a curtain yet, it's a tension shower curtain rod with a nice sheet folded and clipped over them, that fits into the french door opening. Putting hardware into the door inset would have been a pain, and the shower curtain rod was an easy solution I didn't have to hire a handyman to install. Keeping that extra bit of light out does make a difference.