Just so I can wrap my head around this for future reference, Kirk, when you say trap to belly are we leaving the belly wider than the back or the other way around?
With glass limbed bows, it's more common to trap to the belly side making the belly side narrow. I start at the tips with an aggressive Trap of as much as 15-20 degrees, and then less as it moves to mid limb. So the finished product is a spiral shape going to the fades. I do it all by eye with a palm sander, and have no specific shape i'm looking for.... It also reduces mass weight in the outer limb and increases performance considerably.
Kirk