Howdy all
I don't remember if I read this on this list or one of the other 5 smart forums I read?
HOCKEY PUCKS ! ! !
Plain black, rubber, NHL pucks (.99/ea at Sports Authority)
Put them in your freezer for 24 hours (remember basic physics, heat expands, cold shrinks)
Pound them into the ends of your tubes with a rubber mallet.
They will be in there forever.
I am going to use hockey pucks as a base for mounting previously mentioned LED trailer lights. (Still working on wiring diagram)