This DCF (A.K.A. cuben fiber) design is light enough for a NASA mission. Except, don't plan on taking a lighter with you on a space shuttle.
The main compartment is 10" x 6" x 2.5", about 150 cubic inches, or a bit under 3 liters, with an easy-access phone or snack pocket, which is big enough to handle most smartphones. On its own, it weighs only 1.7 oz, including .5 oz removable, retracting lighter cable. Slip it straight onto most existing hip-belts or upgrade to a fashionable Comfy Strap.
All vulnerable seams have been taped to ensure strength and water-resistance.
Comes with a removable, adjustable strap. Comfy Strap sold separately.