In the days when fixed choke shotguns were all you could get, there were various options for "spreader" loads or brush loads to be used at close range, to mimic the effect of an open choke on patterns. Various approaches were used - inserting card stock dividers in the shot column for example. I even saw square shot available for reloading, don't know if it was ever commercially loaded or not. I used to slightly flatten round lead shot with a hammer to load my own spreader loads, and that definitely would open a pattern fast.
The last 'spreader' load I saw was one sold as a defensive load (can't recall if it was from Federal or Winchester), and it used a post molded into the center of the plastic wad/shot cup to open up the shot charge faster. A similar approach is used By Polywad today for upland game loads - http://www.polywad.com/spredr.html
Lightweight, flat projectiles fired out of a shotgun are going to spread really fast, and lose velocity fast as well, and from the standpoints of patterning and penetration, be pretty much useless...