I spied these on etsy today and would love to have ordered one but it wouldn't get here in time before we leave, and its fun to make your own!
I used scrap fabric and rice on one, plastic pellets on the other. I prefer the rice...as its safer and environmentally better, but the plastic is fun and you can see through it and shift through it easier. The window is vinyl from JoAnn's.
I did shrinky dink animals for the rice one, and random house objects for the other, and they will be a good little toy for the boys on the plane I think!