The pocket kits I have built, I chose to pack into Pelican Micro cases.
I have previously found that items carried everyday in soft bags tend to get degraded by constant squashing and abrasion. The hard cases have kept the contents in better condition much longer. They also keep the items dry during brief submersion.
That 1040 micro case is about six inches long and fits in a cargo pant pocket.
I have carried the one in the image all over the world.
Contents list:
Fresnel lens
Plastic bags
Fishing gear, hooks, lures, floats, line
Trace/snare wire
Prince pocket torch burner
Solder
Ferrocerium rod
Magnesium rod
Pencil
5 Minute epoxy sachets
Fred can opener spoon combo
Micro hacksaw
Survival cards (spear points/heads, saws, hooks, jags), Scalpel blades
Alcohol swabs, bandaids, antibiotics
compass
water sterilization tabs
glucose tabs, stock cubes
whistle
cord
Signal mirror
Safety pins, rings, screws, eyelets
Sewing kit
Steristrips
The other gear usually on me is:
Multitool (Leatherman Charge TTI) - with driver bit kit
"Rescue Me" Personal Locator Beacon
Sawyer mini
Streamlight Sidewinder Compact II