The stuff I’ve made has been sewn by hand. As in needle, thread, two fingers. (Two fingers that probably wonder why I’m so mean to them.) Anyone who claims they can’t make or modify what they want because they lack a sewing machine, shouldn’t let that hold them back from what they want to achieve. Remember, mankind clothed and sheltered themselves and carried their goods around for millennia without benefit of sewing machines. (Take a look at the clothing made by the arctic peoples. Awesome doesn't even begin to describe it. There is design and tailoring involved that would put a Saville Row tailor to shame.)
Don’t get me wrong, if I had a machine I would use it, but I don’t (yet). At some point I hope to, but for now, I don’t want that to hold me back from modifying or making stuff to suit my needs. I also spent 4 years of 4 hours a day on the train commuting to work. I tried to use that time as productively as possible, so I got a lot of sewing done.
(I should say that I do have a sewing machine, but I just use it for light stuff - tarps, stuff sacks, quilts and underquilts, soon a hammock. It won’t work for heavy material like Cordura and webbing though.)
I guess I’m just one of those people who is rarely satisfied with stock anything, has an insatiable desire to improve, a compulsion to learn and a drive to make stuff, and adapts to overcome any obstacles.
I use Coats Upholstery thread (far, far better than Guttermans in my opinion) and embroidery needles, also known as crewels. The eye on them is a good size to get coarser thread through. A relatively fine needle like that I found works better than a larger needle. Counterintuitive, but there you have it. Only put a knot in one end of the thread, as that gives you an out if you need it.
Some of those rubber thimbles you find in office supply stores (one for your thumb and one for your forefinger) will aid you in getting a grip on the needle as well. I really don't like metal thimbles. I understand how they work in theory, but just find them awkward. Not to mention that they don’t seem to make them for burly giants.
A pair of needlenose pliers (I use my Leatherman Wave) will also assist you in getting the needle through more difficult areas (usually the outer edges of webbing) or through more built up areas.
When possible, I usually try to staple the webbing on to the material. A dinky little office one won't really cut it, you need a pretty heavy duty stapler. Pins or safety pins don't work very well in cordura and webbing. Binder clips can also be a real boon.
It’s much, much slower than using a machine (obviously). Frankly it’s tedious and boring. But it’s also quite meditative, and it’s one of those activities that I can do in “dead time”. Sitting in the passenger seat of a car, commuting to work, waiting for a client to show, etc. I also always know that I will end up with something very usable at the end, and I’ll also have the tremendous satisfaction of knowing that I made it. It won't be pretty, but it will work. (And I’m not making couturier dresses, but stuff to wander around in the woods with. How it looks isn’t so important.) Everything I’ve done has proven to be very strong. Now mind you I'm not crawling through the rubble of an urban battlefield on a daily basis, but so far my hand sewing has held up very well. I recently took apart something that I had done myself and at the same time took apart something very similar made by a very reputable manufacturer on a machine. The machine made item came apart in seconds. What I had made was a total pain in the bottom to take apart, taking me many minutes.