So, after making a saw blade knife (https://www.instructables.com/id/Saw-Blade-Custom-Knife/) I decided that I'd need a belt sheath if I wanted to carry it around with me. Using some very basic tools and an old leather jacket; I'll walk you through how to make your very own leather jacket knife sheath!
Step 1: Tools and Supplies
Ruler or Straight Edge
Two Heavy Needles
Hot Air Gun or Hairdryer
Knife the Sheath will Hold
Old Leather Jacket
String/Thread or artificial sinew (that's what I used)
Step 2: Make a Pattern
First, I laid the leather over the knife to try and get an idea of how much leather I'd need for the top/cover piece and used my ruler to mark straight lines with the awl. It turned out that I needed a little over an inch of leather to cover the knife and leave enough room for stitching on both sides. Next, cut a piece of leather that is the width of the original piece plus two inches; you'll need the excess later on for the belt loops. Once the pieces are cut, mark them to give yourself a reference line for stitching. The space between your two lines should be smaller than the top piece of leather; if it isn't, you've done something wrong. Remember, we're making a pocket for the knife to fit into.
Step 3: Just a Little Bit About Stitching
I've found that a saddle stitch works best for me. It's easy to do once you understand the basic concept, looks nice, holds up to a lot of abuse, and makes hiding end knots easy. With that being said, sewing the leather is the most tedious part of this project so, I'd recommend finding a movie to watch while you do it. If you haven't done this type of stitching before, I'd also recommend searching YouTube and Instructables for guides on how to do it before hand. Again, this project requires a LOT of stitching and doing it right will make the difference between a finished product that works and one you can be proud of.
Step 4: Sew: What's Next?
Yep, sewing. Lots and lots of sewing. Make both of your sides straight and angle the bottom of the piece to mimic the curve of your blade. Keep a close eye on your guide lines as you sew and remember that the top piece should bunch up a bit (again, we're making a pocket, if the top piece is flat your knife won't fit!).
Step 5: Belt Loops
Lay your sheath over a large belt and mark the width so you'll know how large to make your loops. When in doubt, always leave more material than you think you'll need. It's easy to remove excess, almost impossible to add material. Cut away excess (following your stitching and leaving about 1/8" beyond it), put another small piece of leather below the flaps, mark where your holes will go, and sew around the holes. Adding leather and sewing around the holes will strengthen your sheath and increase it's life span. Once the sewing is done, trim away the excess leather, use your awl to make holes at either end of the belt opening, and then slit the leather between those holes; this is another way to keep your leather from tearing.
Step 6: Time for a Bath (Wet Forming)
Grab a cup deep enough to completely submerge your sheath, place your knife in the sheath, and give it a hot water bath. Leave the leather to soak for a few minutes. When you remove the sheath, the leather should be soft and easily formed around your knife.
Step 7: Seinfeld Hates This Part...
Shrinkage!!! Use your hot air gun to help dry out and shrink the leather to fit your knife; specifically the blade. Don't worry about forming tightly to fit the handle, you'll probably want that part of the sheath to remain lose but, focus on the blade. When the leather gets hot enough, you'll see it shrink down around the blade. The last step is to simply allow the sheath to dry with the blade inside. Once the leather is dry, you have a finished sheath!
Step 8: Finished Product!
Congrats! You now have a custom sheath for your knife!