I like quackingplums idea, instead of fitting the hopper into a high/low rise, just thread the hopper to fit into the marker itself, or perhaps latch it on or find some other way to secure it. Also, make the thing long, like really long, keep the same or smaller head on visual profile, but extend to hopper back and foreward more to increase capacity, maybe drop a support to the back of the marker to balance it and add a second motor to aid the balls in moving toward the neck. really anything to reduce head on profile and increase capacity would be nice.