Seattle Fabrics is not far from my mothers house in Seattle and I go there every time I visit. The types and colors of fabric, the toggles, zippers, buckles, webbing and everything else they have is mind boggling. It takes me 2 hours to get through the store every time. They have hundreds of little drawers with every conceivable shape and size of outdoor equipment hardware. I don't think half of what they have in the store is on their website. I usually walk out of there with at least an extra project that I promptly deliver to the basement storage box when I return home.
In the late 80's, a friend showed me how to sew fleece hats and gloves when were working at a remote winter lodge. That evolved into us making clothing, tents, packs, stuffsacks, and anything else our minds could come up with. Nowadays I mostly just repair gear for myself and friends, repair replace zippers, make a few hats and of course stuff sacks and rain flys. We've had the same old $99 singer sewing machine for 30 years now and somehow it still works after sewing through thick webbing, nylon, zippers and anything else imaginable. We bought a serger, this time the $199 singer, about 20 years ago for sewing polyester fleece garments.
Sewing opens up a new world of customized gear. You can modify anything you own already or just start from scratch. The best thing is that you can copy practically anything you see and improve upon it. There's so many pieces of gear I've had over the years that were improved dramatically just by adding a single buckle in the right spot. The only other similar experience I've had is when I learned how to weld. That opened up a whole new world too.
Mark