Like the ones you buy professional for real slides. They are kinda like a sleeve you slide your slide into. So it would be two separate pieces joined together or one piece folded. So a sleeve you would cut in half, front & back to make two frames or put foam inbetween to make the shaker.
Long winded, that was what I meant by sleeves.
I am not into shakers really... I like beach themed shakers with sand in them and shells, etc... maybe ones with snow?? But with other materials, they are cute and all, but I just haven't gotten into them!!!