Opps, not plasticcote (that's a brand of paint), it's Plastidip http://www.plastidip.com/  Most larger autoparts stores carry at it or Amazon.com I'm sure has it.

It's like the stuff used to coat the handles of pliers, originally they sold it in a can that you could dip stuff in to coat it.  They now also sell it in spray bottles.  I've used both.  When I have flexible rubber parts that are cracked from age I use it to spray (several coats) over the old rubber (inside and out) to form a new layer to restore some structural integrity and seal up the cracks.  Like on old rubber ducts that connect the outlet from a blower to defrost nozzels and similar things like that.  For some parts that aren't being reproduced it's the only way to save them if there's enough of the old left to form a skeleton to spray over.  The flock stuff suggested would certainaly be an optino.  Or you could buy some sheets of self-adheavise felt and line it with that.