The curve I am not worried about making...just take 30 rds and use masking tape to put them together and use a compass to trace the other side.

In my mind the hybrid I am looking to make has the rounded end to dump the rounds and stage them...a curved channel with markings for amount of rounds in the channel. At the bottom instead of having a mag specific cutout have an open bottom for universal fit, then have some form of holder do push down on the mag