Another of the "ten essentials" that I do not carry is a repair kit. I'm not exactly worried about my thick spectra pack ripping. Most of my really important gear is pretty bomb proof and for the rest, if I keep it in good shape it should not fail and if it did, it would give me a chance to improvise. So no duck tape - yuck, if you use duck tape on nylon fabric you'll wish you hadn't. I'd rather rip a down jacket and lose feathers that can be replaced than put adhesive on an expensive jacket. I suppose a needle and thread might help,
BUT
today I had to hand sew a piece of gear. The buckle broke (slammed in car door) on my crazy creek chair and had to be replaced, and one of the rigid stays had torn through so I stitched it down, all with boot makers thread. Besides repairing an air mattress, which is pretty much impossible while camping, I haven't "repaired" any camping gear nor had any camping gear in need of repair for a very long time, like over ten years.

I used to carry eye glasses repair stuff when I had $200 titanium frames that kept falling apart. I went to Wal Mart and bought a pair of glasses with poly carbonate lenses and plastic frames that envelope the lenses, for $68.

I do carry a Gerber LST knife. It weighs around 1.5 oz but has a really nice wide blade maybe 2.5 inches long. I guess thats my repair kit. Oh and I often carry a tiny pair of those "tick tweezers" - lot of tool there for not much weight.
Jim