Regarding my stitching technique. I am not very traditional here. I use a punch and space my holes 1 cm apart. I pick where I want to start the process and punch the holes using the smallest punch on a rotary. I measure with a ruler and make a dot at each 1 cm interval. I use a grove tool to cut a goove through the holes. I just got this tool and this is the first sheath I used it on.
So once I get my holes the way I want them, I lay the piece first on the opposite side or piece and I use an awl to make a tiny mark through the existing hole...a transfer...then I punch. I hold the two sides up to the light and I should see light through all the holes.
For the welt, I pretty much do the same thing. However, you have to be careful because, as in this sheath, if there are differing numbers of layers, the holes slip out of alignment. I used to do a lot of fussing around with that until, duh, I got the brilliant idea to make the hole in the welt a size bigger...problem solved. Again I hold up to the light.
Then I use Barge Cement to stick the welt to the piece. "Why, how do you ever line the holes up? Using contact cement?" you ask. I have a huge box of small nails with flat heads. I poke the nails through the piece in just about every other hole or sometime every hole. Then I slide the second piece down on the nails, being careful to just get the second piece started. Then I push it down easy until I am about a quarter of an inch and them start either in the middle and work out or at one end and work to the other. DO NOT start at both ends and work in, you'll get a wrinkle. Repeat until you're all glued up. Hold up to the light and look for the daylight in all the holes. Then I pound it really hard with a nylon mallet...smooth surface. I know a guy who has a cobbler's hammer...that'd work too.
Now to actual stitching. Because my stitches are so course (1 cm) and my holes are so large (unlike an awl) I double up a waxed, braided thread. Then I start at the top and leave a good 6 or 8 inches free at the bitter end. I stitch a running stitch down one side and then back up...faking a bone fide saddle stitch which is two needles going at once. Then I come back down 3 or 4 holes and cut. Then I take each of the original ends, thread them in the needle one at a time, and take each piece down two or three holes and cut. Then I hammer them flat with a mallet.
Once I have it glued and stitched, I trim with a knife and sand like crazy with course sandpaper. Usually by laying the sandpaper flat and grinding the edge down on the paper against the table. Then I finish up with finer paper usually in the hand.
Not exactly elegant but all hell for stout. I make the holes no closer than 1cm because I do not want to weaken the leather by removing so much material. Some day, I want to stitch in a more traditional manner but this works so well, I just keep doing it and some people like it. I could never get away with selling something with stitches like that though.
