Step 1: Pattern Making

I did a little bit of research to know what an actuall holster looks like and how it is put together.
Afterwards I used some sketching paper und cardboard to construct and create my owm pattern.

Pic. 1 and 3 show the back piece which joins all 4 straps.

Pic.2 is the rest of the pattern including schoulder pieces, single straps, ammunition pocket and gun holster.

Pic. 4: I wanted the holster to a) look nice from both sides and b) be stronger and not so wobbly. Therefore I cut out all the piece twice and glued and sewed them together. This way you'll have leather on both sides! :)

Pic.5/6 To get nice edges and to not have this fake leather look on 'em I used a marker in the same color as the leather itself and painted them. U can use a permanent marker, a sharpy or copic marker. WHatever you find ;)

Step 2: Ammunition Pouches

Fake leather itself is thick, but not strong enough to stay in a boxlike shap on it's own. So I used 2 pieces of think plastic to create a little support. I then glued leather onto it and but every piece for the ammuniton pouches together.

Step 3: Gun Case

Some deal gun case. 2 pieces of leather put together for more stiffness and a better look.
Rolled it in and fixed it with sewing and superglue.

Pic.5 gives you an ida of the holsterpieces coming together :D

Step 4: Finished Holster

Before finally glueing the straps to the back and using rivets to fix everything+decorate the details, be sure to test wear it and alter your straps in it's length and shape to your body!!

There you go! Booker Dewitt Costume holster <3

Now have a few cosplay photos XD...