The Use of Plastic Bottles.
I have been using cheap, lightweight funnels made out of plastic bottles (food grade only please) 
such as two liter soda bottles. Just cut off the bottom of the bottle. You can also heat the rough 
edge with a candle flame, to make it stronger and smooth out the edge.
One of the nice things about making your own, is that you can choose the size of the funnel spout; 
most store-bought funnel spout openings are too small. A soda bottle has a nice large opening.
They are great for mixing powered drink mix into your plastic canteen bottle.
The other way of course is to use a plastic wide mouth container.
(You DO know, never to put ANYTHING but water, in a metal or aluminum canteen, due to corrosive 
factors) 

Two or three liter bottles also make a better container for carrying water to dry camps such as at 
PHILMONT, (or for use in-camp for meal preparation) rather than having two Scouts carry a 
HEAVY two and one half gallon, or a MURDEROUS five gallon container.
(One of our 5 Gal. collapsible plastic containers was dropped and broke open.)
This way everyone can carry extra water and you can attach it to the outside of your backpack with 
two half hitches around the neck, and a bowline on the other end to one of those light duty 
carabineers. You might also want to strap it down so it will not swing.

While packing for a backpack outing, I wanted to bring a spray can of OFF! insect repellent, but it 
had an open cover. (The spray button is exposed on the top)
This is a good way to have a nasty mess in your pack, and melt all the nylon into a lovely goop.
I found a bottled water container and cut off the top.
I also used a candle flame to shrink the edge down to the exact size of the container.
This is safe because you will not heat the can too much. I then had to poke an air vent-hole with a 
small hot nail to facilitate getting it on and off.
Now I have a lightweight cover for the spray can.

You can use the top of a one-gallon milk container as a funnel for filling your automobile radiator; 
it has a nice LARGE hole, and just fits inside.

     David Lagesse
     Just Us'ens
     pineapplefish56