What features would you like to see in a small pack for fly fishing

I'm designing an ultralight pouch for fly fishing and would like your feedback. The concept is a small pack that can be attached to your pack harness, belt, or worn around your neck and carry one small fly box (with a few bells and whistles). What features would you like to see in something like this? So far, I already have a drying patch, hemostat holder, pocket for floatant, some lash points for other gear, and internal pocket for leaders, tippets, etc. What else?

The goal is to make it under one ounce. My first prototype was half an ounce. Not bad, eh?