Here are some of the basic tools you'll need
Layout your pattern to see how much leather will be needed (for 1911 style holster thats about 11" x 9 1/2")
Next dampen the leather with a sponge or wash cloth.
Using a pencil, pen or stylist trace over your pattern.
This will leave an indention in the leather, this will serve as the cut line of the pattern.
Using a utility knife cut out the "front side of the holster to just past the 1/2 way point.
Fold over the gun and make adjustments for fitting. Doing it this way will let you make "on the fly" adjustments to account for things like leather thickness, how deep the pistol sits in the holster etc.
When fitting holster fold it over till you have about 3/16" to 1/4" of excess beyond the pistol.
Remove the gun, fold leather over and trace outline. (I don't normally use clamps but I needed a free hand to take the picture)
Now cut out the "back side" of the holster.
Now set your stitching groover for 1/8" and run it along the front edge.
If you don't have a groover measure and mark a line 1/8" from the edge. This is your stitching line.
Using the overstitich wheel mark where the holes will be punched for sewing.
Using three prong nippers is the fastest way to punch the holes.
Another option is to use a 3 or 4 prong lasing chisel or you can punch the holes with a leather awl. I also know of a few folks that set up a small bit for their Drimmel Tool or drill press. All of this is done on the front side only, we will get holes in the back side later.
Using a Swivel knife score a line marking the border of the area to be tooled. (Here I'm using a depth gauge to make sure I keep it even along the edge.
When stamping you will need a heavy, smooth, surface to work on. Most professionals use a 1 1/2" thick marble slab. Long story short I now have a 12"x18"x 1 3/4" steel plate.
Another thing that makes stamping turn out much better is a heavy (16-20 oz) maul or mallet. Using just one sharp blow to make the impression instead of using a lighter mallet and having to strike the tool multiple times.
Try to make sure the "rope" in the basket stamp lines up. If you find it is getting hard to leave a detailed impression dampen the leather again with a wet rag. Your tool should leave a detailed impression that looks almost burned into the leather. If your leather is too wet the impression will not change color and will not be as detailed.
Now go around the edge with an edging/camouflaging tool to blend in the basket stamp.
Now that the front side is tooled & has all the stitching holes it's time to turn our attention to the back side of the holster.
Fold the holster over and make the front side line up flush with the back side as best as you can. If there are areas that just aren't flush and lining up exactly don't worry we will take care of that in a minute. Push the awl through the holes on the front side and make pin prick marks on the flesh side of the leather. Punch holes along these marks as you did for the front side.
Next I open up all the holes by pushing the awl through all the holes. This makes it just a little easier when sewing.
After that is done I "tack stitch" the holster together. For this I only use one needle. I push the needle through and to a zig zag stitch all the way down the holster. You don't need to pull the thread really tight for this just snug enough hold the holster together.
As you can see it ends up looking like I've skipped every other hole.
When I get to the end I go backwards over the stitching to secure the end. If you only have one needle this is how you will end up sewing the holster. You zig zag down and back to produce a lock stitch.
Using the front side as a guide trim any areas that have excess. When hand cutting holsters or any leather project that will be folded over and sewn together it is almost imposable to get both sides to line up perfectly.
First figure out how far down the holster you want the attachment to go and where the belt will ride. Trace the back side of the holster onto the smooth side of the attachment leather.
Once it is cut mark the stitch using the awl.
Using your carry belt place it where you want the holster to ride. Mark where the belt rides and add the thickness of the belt to each side. This will be your stitching line. ( For this belt I added 3/16" on either side of the belt, thus my stitch lines are 1 11/16" apart.)
Now that we know where the belt will go, some of the leather along the stitching line must be removed. Here I've marked the corners of where I going to cut using a 3/16" hole punch. Using my nippers I've also punched holes along the rest of the edges that will be sewn. I've also marked the belt sew lines using the over stitch wheel.
It should end up looking some what like this.
Now using a zig zag stitch attach the holster and use the awl to mark the holes on the body of the holster.
Just a short word about dyeing your project. There are about as many methods of dyeing leather as there are people that do it. Some say you should use only Neets Foot oil, some say you must treat the leather with a conditioner after you dye. I simply use a dobber and apply 3 or 4 coats to the smooth side and 1 or 2 to the flesh side.
Here I'm using a Mid Brown. As you can see it has a reddish hue to it, by trial & error I've found that the wetter the leather is when it is dyed the redder it will be. That being said each dye & hide is different, read the directions on the bottle.
Thread a needle on each end of your thread. ( I like 00 egg eye harness needles) Starting with the second hole on the lower portion of the attachment pull one needle through 'till you have an even amount on both sides.
Now go through the first hole (edge hole) with each needle from opposite directions. Back through the second hole. Continue sewing this way all the way around lower triangle. (Each needle going through the same hole from opposite directions pulling the stitch tight every time.)
After you have gone all the way around sew backwards over the stitching for 3 or 4 stitches.
Sewing backwards eliminates the need to tie off the ends in a knot. This is also how it is done with a sewing machine. At this point I like to snip the thread about 1/4 from the leather and burn the excess.
Now do the top portion starting with the lower stitching and working your way around the top of the holster. When you get to the top edge corner fold the holster and sew all three layers together.
Sew down to the end of the holster and back stitch as before. This takes about 6 feet of thread.
Now that all the sewing is complete it's time to mold the holster to the gun. I'm sure there are other ways to do this but this is how I do it. Get the holster soaking wet. I usually hold my finger over the hole at the bottom and fill the holster with warm water and let it soak for about 45 seconds to on minute.
While getting it wet wedge your thumb under the belt loop and force it open. Now slide your belt through to mold it to your belt.
Leaving the holster on the belt now force the pistol in the holster. This should be a fairly tight fit. I usually have to cock & throw the thumb safety to keep the slide in place while I'm putting the gun in the first time. Just remember this leather has never been stretched like this and it will loosen up.
Using the handle of the awl (or one of your other tools) press the leather into all the nooks and crannies of the pistol. Because this holster is tooled the molding does not show up as much as a slick leather holster. If you are worried about putting your baby in a wet holster a light film of gun oil on the slide does wonders. I've been using my 1911 for this for over 10 years with no ill affect.
The last thing I like to do is flair the top for easy re-holstering.
After everything is molded remove the gun and belt and let the holster dry. Don't "help" the holster by putting it near a heat source, just let it sit at room temperature till it's dry. When it is dry it will be very hard and stiff. At this point I apply a thin coat of neutral shoe polish to condition the leather and buff it.
There you have it. In less time then it takes to watch the Lonesome Dove you have a holster you can ware with pride for years to come.