now cut slits into the top of the can and fold them out.
place top of bottle on can top and mark out where the top of the can hits the bottle.(you may want to cut a little above the top since it is easier to trim more than it is to add to where you cut off to much.
slide can through bottle top so that the flaps of the can are on the outside.
add tape
then slide it down into the bottle(this may take a little effort to do without bending up the can so take your time with it