Although Mainly used for coarse fishing rigs, more and more trout anglers are using these foam rig winders to hold their casts.
If you wind a cast on with the flies already tied on, then you simply stick the hooks into the foam.
If you are winding on a pre-tied cast with no flies, then just cut a small slice into the edge of the foam and tuck the loop end of your cast into the slit to hold it. Some people just pin the loop end of the cast into the foam with a staple.
None of the kinks associated with traditional cast holders.