Welcome to the Quilting Board!
Great gift for sewing friends.
I've made a few of those with velcro, I have several machines so I needed more than one. I also have made them for gifts.
I wonder if you used elastic and then just slipped it on it that would work. Not a fan of tying it as my DD would just untie it when ever she notices it. Maybe I would try the velcro and see if she would take it off then. I think it would be hard to put plastic in the thing if you have to turn it right side out. Has anyone done this yet?
When I was in high school (l955) our home ec teacher had us make 1-1/2 x 2-1/2" pin cushions that we put elastic on and they fit on the top of the machine, always out of the way and handy. Since the machines are so much bigger now, I just made a smaller one, put velcro on the bottom and the other end of the vecro on the machine and there it sticks, again, up out of the way...works for me!
Why didn"t I think of that? lol