The best books on this sort of leather work were written by Al Stohlman (Hand Sewing Leather, and The Art of Making Leather Cases Vol 1 are good). For the leather I'd suggest finding a nearby Tandy Leather store and seeing what they have available. One can mail order leather but until one has some experience it might be best to see it first hand and look at the thickness and at the quality of the leather itself. One also needs some tools. The picture below shows the basics, left to right: cement, a very sharp X-Acto knife, an overstitch wheel, beveler, awl, groover, thread and upholstery needles. For the thread I prefer linen, although most people use nylon. It has to be heavy waxed thread for leather sewing. Tandy Leather has tools and they mail-order. I don't have anything to do with Tandy other than buying from them over the past 16 years.
First step is to make a pattern out of paper. I wanted to make a simple case that would hold four tension wrenches in the front in separate compartments and 4 - 6 picks in the back in two compartments. The best designs for leather use more leather and less thread to hold things together. For this design it uses one piece of leather except for the piece that will hold the tension wrench. Need to cut the leather straight to have straight stitches (more on that later).
After the paper patterns are worked out they are transfered to the leather. I just use a lead pencil to layout the lines.
One thing about project like this is one has to think ahead, before things are glued up or stitched one might have to put in snaps and such. Regarding snaps, I decided to use a snap to close the flap. For that a person has to punch a hole for the snap, then use a special punch and anvil to set the snap. The bottom snap has to be set now as there will be no way to install it later on. But, the top snap should not be installed until everyting else is done as depending on how the stitching goes, the leather bends, etc., the proper location may change. Base the location of the other half of the snap on where it lines up perfectly, not where it should be in theory.
Next step is start cementing the parts together. The cement gives strength to the seam and also holds things together while sewing. I like Barge cement. It is like rubber cement: apply to each part, let dry 15 minutes, press together.
After the leather is together it is time to stitch. The easiest way to do this would to take it to a shoe repairman or a saddle maker and pay them to use their sewing machine. A real leather sewing machine to sew leather like this runs ~$1,500 and up. What I did here is called saddle-stitching and is done by hand. The first step is to use a groover to carve a small grove where the stitch is going to be. They are adjustable to determine how far in the grove will be from the edge of the leather, or one can do it against a straight edge when they have to (as below when the stitches are not next to the edge of the item).
It may be easier to "case" the leather before grooving it. To case leather means to dampen it evenly with a sponge. Dampen it all, uneven wetting can leave spots.
After grooving, the location of each stitch needs to be laid out. For that an overstitch wheel is used by pressing down on cased leather and following the groove. That leaves a dimple where each stitch needs to go. Spot each dimple with a pencil if they are hard to see.
The next step is to do the actual sewing. For saddle stitching one uses a single piece of thread with a needle on each end. To thread the needles, thread a needle as one normally would, then pierce the thread with the needle about 3/16" or so from the end of the thread.
Then pull the pierced part of the thread down past the shank of the needle.
Then roll the end of the thread around itself. Some beeswax can be used to make the thread stick if need be. The thread should appear as below, with a needle on each end. The length is from experience and it is OK if one runs out of thread during a stitch.
At this point you can sew it two ways (three counting taking it someone else). One way, and not a bad idea first time out, is to take a small diameter drill bit and pre-drill each hole. The stronger way to do it is with saddle stitching where an awl is used--that does not remove leather, it separates the leather and then it closes back and makes a tighter seam.
To saddle stitch there has to be a way to hold the leather while it is being sewn. Saddle makers use stitching horses--big things a person sits on with a lever that adjusts the clamp, Tandy Leather sells a small version to clamp small projects. I ended up making the gizmo below out of a Jorgenson parallel clamp. Some wooden jaws lighted with leather were added to the top and a cross-piece at the bottom. In use one sits in a chair on with the cross-piece under one's legs. A twist of the clamp handle opens and closes the jaws.
The leather is clamped near where the stitch starts then the very sharp awl is held with one hand along with one of he needles. The awl is punched through one of the over-stitch dimples, retracted, then the needle in the right is passed through the hole to the left and half the thread pulled through. Then the next hole is punched from the right and a needle passed from the right to the left, then the needle that was already on the left side is passed from the left to the right, then the thread is pulled right with both hands. The process is repeated until the stitch is complete. At the end, double back from the last hole to the next to the last hole then cut the excess thread on both sides. This is fairly thin leather for this sort of stitching. If one finds a needle hard to pull through, one can use a pair of pliers. Have extra needles, the eyes break occasionally.
Here is the pouch with all the stitching and the second half of the snap added (after, and only after, the hole for it is found by seeing exactly where it needs to line up with the other snap).
Next step is to finish the edges. I like to use a belt sander with a 220 grit belt to smooth and straighten up the edges. Then they can be rounded with a beveler and then finished by burnishing the edges with a grooved piece of wood spun around on a drill, or in this case on a small restored wood lathe I found in a junk store a few years ago.
To make the pouch hold on to the parts one molds the leather around the parts. The leather is dunked in lukewarm water, then the parts are inserted and a rounded stick (or a deer antler tip) is used to push around and form the wet leather around the parts. The wrenches can be removed so they don't rust. Let the leather set until dry, which will be at least a day. Do not repeat this process, each time the leather gets wet some of the oil is washed out and it can dry out and become brittle.
The molded pouch is below:
After it is dry it is time to finish it. One could use neatsfoot oil for a natural finish, but that tends to weaken leather if over-applied and it can soak onto your clothing and such. Here I'm using some leather dye. It is applied with a wool dauber. One applies it in a circular motion as it soaks into the leather. Try not to get it on your skin, it does not come off easily. Don't worry if it gets on the snaps, it will wipe off later. Some people dye then assemble, but I prefer to assemble everything first.
When the dye is dried it can be buffed with some lambs wool, or with a terry cloth towel. After the dye is dry the last step is to seal it. That will keep the dye from rubbing off. Here I'm using some spray sealer from Tandy Leather. Apply it sparingly, an over-thick coat and it will get sticky on a hot day. After it is dried buff it with some lambs wool, or failing that with a cloth towel.
Here is the final item:
By molding the leather it means the parts will not fall out when turned upside down:
Decided to add two more picks to it:
Anyone wants to give it a shot I really suggest reading Al Stohlman's books first and I would be happy to answer any questions.