I just finished making my new pack. It's a modified G4. I found the directions on this terrific site, GVP Gear. The instructions were wonderfully precise and detailed.

I made a prototype pack in June, and trail-tested it all summer. I decided on modifications, subtractions, and additions, and then made this pack incorporating all that.

MODIFIED: A beefier hip belt, padded with Nu-foam. Raised the side pockets 2 inches to allow easier access to the lower pockets. Shortened the top a few inches. I Padded the straps with the pieces I trimmed from the z-rest. A full pocket for the z-rest/back pad instead of just the ends. nylon pockets instead of mesh.  

ADDED: The front flap with a large pocket. Loops to carry hiking poles. The purchased zipper pouch on the belt. A sternum strap. D-rings on the shoulder straps.Interior mesh pockets on each side for three more sections Z-rest in each pocket. An ID/money/key pocket in the inside top of the back.  Drawstring side pockets below the side pouches. I bound all the seams. Yes, most of these things add weight. But I wanted them. The pack weighs just over 1-1/2 lbs.

OMITTED: Thumb loops. hydration tube guides. The roll-top closure.

My new pack is finished!
Underneath the flap
strap side of the pack

SOME OF THE DETAILS:

My good friend Doreen did the beading for the pocket, and I added the GCHBA patch.
I added a money/ID pocket that closes securely with Velcro. There's  a cord with a key ring that goes in the pocket, too.

I added drawstring pockets below the side pockets. I can access them while wearing the pack.

I added loops to hold my hiking poles. I can reach these while wearing the pack.
The pole is held by a webbing loop at the top of the back.

The bottom of the pole is secured with an elastic loop attached to the bottom of the strap.