The small top tube bag behind the stem is big enough to hold my gloves, sunglasses, and other small things. The frame triangle holds our first aid kit and all my bike repair stuff besides my spare tire. Plus they add a touch more visibility to my otherwise grey bike.
The cloth I used is the cheapest PU coated ripstop nylon on ebay. I also had some velcro and webbing loops left over from previous projects. Finally, I extracted the zippers from an old pencil bag that I lovingly used throughout middle school. So, like most of my projects, time ended up being by far the most expensive component.
I started by making cardboard templates. I also put marks where I wanted the zipper and velcro straps to attach.