Silicone measuring cups. Take a canister to a place like Bed, Bath & Beyond or Walmart and find a cup that the canister fits. Cut off what you need from the cup. Based on the cups I own, I'm guessing that a one or two cup size should be about the right inside diameter.
Hobby stores might have copper sheets. Find an appropriate thickness & cut to fit.
Velcro straps. Good for use on your pack too.
http://www.velcro.com/products/ties-...ize=27in x 1in
Good luck!
Wayne