Got my Butt pack and IFAK bag from Architect today, and I'm in the process of packing My FAK into the IFAK bag. It'll make things a lot easier to find. It's a S.O. Tec bag, SOF-IMAP-PI with pouch insert that rips out. I'll be putting flat items in that part.

The butt pack is a Blackhawk bag and actually would hold my 511 Push pack. It will probably go on the bottom of my TT pack to hold my cook kit and some other items.