Chuck,

Backer rod is used in concrete work, so try a contractor supply store.

Straws don't work, they split...what you want to use is fuel line material from remote control cars...get it at a hobby shop.

That being said, I find that at about $1 apiece, it's a lot less hassle to just buy 'em already put together.

However, that's just me! :p

If you decide to make them, good luck!

Fish on...

Todd.