I was out shopping yesterday (and found a variable medley of stuff, some of which you may see soon) and found these Zoom-o refill packs for $1 per at Walmart.
After playing with them, I found they fit quite nicely into the Titan's orange rocket barrel.
A very simple mod. All you need is:
Titan barrel
A gun with a large airtank that the barrel fits on
Cut out the baffling AR at the end of the barrel, but leave a small lip around the edge so it catches the balls. Load in up to 5 balls and fire.

When fired, it shoots the balls in a staggered fashion, about half a second behind each other. This allows you to swing the barrel when firing to create a spread of fire.
Ranges, from a Titan @ 60psi are about 25', not great, but it's a shotgun. Arched, this would be excellent to rain down foam death at people behind small walls.