You may wonder why we have plumbers tape in a sewing shop! It is used to seal the ends of metal and plastic boning either filed smooth or after you've capped them with end caps - the tape smooths any remaining rough edges, puts a blunt head on the bone or keeps the caps extra safe and smooths any rough edges.
The way it works is that you simply stretch and stick - it works like florists tape, by stitcking to itself as it stretches over itself.
Once i've wrapped I usually bash with a hammer to get it nice and flat. Trust me it works!