I wanted a nice leather briefcase messenger bag for hauling around all the stuff I need for my profession, as well as my personal defense CCW, but I didn't like anything I could find available commercially. It seemed like anything with the ability to organize things well wasn't classy looking, and anything that appealed to me aesthetically didn't seem to be set up very well for actual use. Having a leather shop make a one-off custom was out of the question financially, in fact even buying domestically was out of the question, so I had to find and modify my own.
Step 1: The Bag
The bag as it came was very nice. Made of thick leather and well mounted hardware, it seemed to be a great foundation. It did lack much ability to organize internally, and the straps and buckles were a bit of a pain to use in practice, but those things would be taken care of. I was able to slip my compact pistol in one of the pockets, but it wasn't entirely secure, and certainly not easily accessed.
The same model can be found on a large online retailer for somewhere around $400, but a little internet-fu found me the Chinese manufacturer's website and a retail price of $126.
One thing I noticed in use before my modification supplies arrived was that the bag was a bit "floppy". It doesn't have the internal flap stiffener under the carry handle you see in some leather messenger bags, so when carried that way the whole bag seemed to slump a little. Part of my aim would be to stiffen the whole thing up a little.
Step 2: Stiffener and Hook/loop Panel
I like the versatility of equipment that has fields of Velcro so one can attach whatever accessories one needs, but I wanted to keep to a minimum the permanent alteration of the bag, so I came up with this solution.
A scrap of carbon fiber sheet leftover from a previous project was cut to size and shape to slip into the bag right next to the center divider, then self-adhesive Velcro was stuck to that.
Step 3: Hook and Loop Goodies
There are a great many options available for accessories designed to adhere to a field of Velcro loops, but what I needed was a way to organize pens and other small items, as well as a safe and secure holster. A major online retailer had the pen organizer, the zippered pouch for small items, and the holster I needed. They stick VERY well to the Velcro.
Step 4: Accessories Carrier
This shows the plate as mounted in the case. I intentionally left the top of the plate detached from the bag's center divider so thin folders and documents could be slipped in there safely. The plate is a slip-fit held in place only by the pinching force of the leather as it comes together at the seams where the sidewalls meet the center divider, so it can be removed anytime to apply new pouches or move things around.
Step 5: Fixing the Straps
As you can see in the first photo, the bag is held shut with some heavy-duty straps with buckles. Very secure, but kind of a hassle and slow to open and close, so I decided to modify the main straps with some thumb latches.
I also ordered the latches from an outfit in China. They seem to be fine quality, but they took a month to reach me, so that's something to consider if you can source them domestically (I couldn't).
I pulled the straps from the bag and used a utility knife to cut them just below the buckles. I actually removed about 4 inches from the length of the straps so they wouldn't hang quite as long. The male side of the latch mounted to the short buckle side of the strap, and the female side to the remainder of the long part of the strap.
Step 6: Done
The straps were then threaded back into the bag, and it's ready to go! I have the classic styling and durability of a leather bag, with the convenience and versatility of a modern fabric pack. I may make further modifications in the future, if so I'll update them here.