Okay, so this is an old post, but I just happened upon it as others may also do in the future.
Besides Al Stohlman's books on making leather cases (an absolute requirement for anyone learning how to make any type of bag, container, pouch, sheath, holster, etc. as the fundamentals are all here to build on), I would suggest a few things.
1. Go to a law enforcement supply store in your area and see what they have for sale. If they are carrying those items, its because they are selling.
2. Note the manufacturers. Look at their web sites for photos or request a catalog with pbotos. That will help you to see angles, cut outs for knobs/buttons/levers on the different equipment, shapes of the items you want to make so you can modify them to your own style, etc.
3. Talk to your local law enforcement professionals and see what their preferences are for their on-duty AND off-duty gear. Tell them why you are asking (custom leather worker) and ask which companies they prefer for their gear and why they like certain manufacturers for different pieces of gear. Any seasoned professional will be able to tell you what they like and don't like, and why. Take some notes. Ask to take photos of their duty-belt gear setup. Although standard equipment (gun, handcuffs, radio, extra ammo carrier (for speed loaders - revolvers or magazine pouch - semi-autos) will be common elements, they may also carry an expandable baton, compact flashlight, Taser, extra Taser cartridge(s), folding knife or multi-tool, pepper spray, extra single or double handcuff case, key keeper, straight or PR-24 (side handle) baton holder, large D-cell type flashlight ring holder, etc.
It won't be odd to find mixed brands of gear on a duty belt (from Safariland, to Bianchi, to Blackhawk, to Gould & Goodrich, to others ... all in black, and appearing to match the other gear/tool pouches - no matter if made of nylon/cordura or leather) because it is a personal choice for many officers who want what works best for them and their individual setup.
Some departments issue a standard brand and caliber of firearm for on-duty use (maybe a Glock 17, for example). Find this out and see if the department has a list of their approved carry weapons for on-duty AND off-duty. Also, check to see if there are any requirements for holster designs, such as it must have a safety strap for gun retention and not be an open-top design. Yes, this is very common for departments to have such policies. This is actually good for you. It gives you the parameters you need to ensure your products meet the departmental requirements, allowing their deputies/officers to buy your product(s). This specializes your product designs, decreases the need to supply a bunch of options to entice a sale, limits your need to buy several different makes & models of blue guns and holster patterns, while allowing you to focus on a few solid designs and improve on ths overall quality of your products.
You will also want to know which sidearm they carry off-duty and HOW they carry it. Do they carry their gun inside or outside the hip, ankle, waste (fanny) pouch, purse, pocket, ...? Knowing this helps you focus on products that you can sell vs. shelve. See why its nice for an agency to have a select 1 or very few approved guns? Less hassle for you. ;)4. After you establish a rapport with one or more law enforcement officers, VOLUNTEER to make a product within your skill set/ability for them and GIVE it to him/her to use, evaluate, and critique for you. That is theirs to keep. By doing that, they will view it as a personal item and not a loaned or borrowed item and will handle it as such and honestly evaluate it to see if it meets their personal requirements and standards. By collaborating with a professional actively working in the field, you will learn a lot as a craftsman and custom fabricator. Ask them to put it through the paces so you can see where, if any, improvements can be made (slant angle, belt loop size, reinforcement points, location of retention snap release, height of holster placement on their on-duty (or off-duty) belt configuration, etc.). This is your research & development stage. Embrace and value it. Its priceless, because without it you won't have the reputation you want, referrals or sales in this area. As a side note, law enforcement professionals are a great and approachable group of very respectable people who work in the public and put their lives on the line for total strangers every time they go to work. However, for a non law enforcement person to get past the public presentation of a law enforcement profesional, it can be a slow start. Building a relationship with them to the point where they will discuss their personal safety practices that they rely on to get them through their shift and home to their families requires time and mutual trust. Be patient. Its worth the investment for the knowledge and friendships you will gain.
5. After you refine your product(s), GIVE him/her the final product they assisted you with and ask them to spread the word for you. Price to sell. Under cut the big names with your custom version of a piece of duty gear as you build clientele. This is how you build up your local custom gear line in a market flooded with longstanding commercial mass producers that have been trusted, tried, & proven. With law enforcement officers, they will not be quick to take a chance to experiment with a product where their life could be on the line and a delayed access to a piece of equipment, due to bad fit or failure to retain the tool properly, could cause a huge safety risk to them or someone else.
6. Once you have a few professional customers in the field using your product, ask them to write a brief review that you can use as a quote for an ad caption. Reward thsm with a small item like a custom key fob with their initials or badge/shield number, etc. on it. A leather cover for a pocket note pad is another popular item. Maybe tool their department's badge/shield on it.
7. NOW you can make a small "improvement" adjustment in your design (better snap, reinforced belt loop, stronger rivet, better thread, thicker or better quality leather, etc.), market it as the "improved" version and increase the price of your custom product to new buyers.
This wasn't patterns. This was just some of my experience that has worked and what works better than straight-out cookie cutter products.In the Leather Crafters & Saddlers Journal, there used to be an ad for Law Enforcement Leather Patterns - "world's only instructional manual ... 19 proven products ... over 200 pages & 500 illustrations, + tips & techniques for $49.95 + S&H @ Legendary Leather, P.O. Box 1325, Fairview, OR 97024."
I cannot vouch for ths book's contents, products, or methods.
NOTE TO ADMINISTRATORS:
If listing that rssource & address is a viation of the forum, pleas edit it out and accept my appologies as I was only trying to help point in a related direction.