Some guys use post-it notes as they already have a glue line. If for a 20 bore, just use sissors and cut the small notes in 1/2 across the glue line, then wrap them around a 1/2" diameter dowel to form a tube. The glue will hold them. Flatten the tube and put them in a pocket in the folwer's bag. Lots of pockets. Trackofthewolf sells one cheaply that is well made of canvas and works very well.
When you want to load, measure and dump the powder in, then seat an over shot wad down into the muzzle about an inch, pull out a tube, round it, and shove it into the muzzle on top of your overpower wad or wads that are pressed down an inch or so. Shove your finger into the cup and it will open to the bore size and re-glue itself. Pour in the shot and seat the overshot wad, then push the whole works down onto the powder. Vary the length of the tube to adjust the pattern. the longer the tube the tighter the pattern until it acts like a slug.
This system can achieve much the same result as the Ely wire and paper baskets of the 1800's, designed to give and did give killing patterns on wilffowl, deer and wolves out to 100yards from non-choked smoothbores. The Ely 'wads' were colour coded for range. Some opened more quickly, others not until after 75 or 80 yards to that distance, they flew like a slug.
You can adjust your paper tubes to act in a similar fashion - it only takes experimentation time and a desire to develope such loads - or you can just load it up with powder, shot and wasp nest and 'take' whatever happens.
