In this step we are going to wet-form the leather to fit the pistol. If you are using an airsoft gun or a blue gun to mold the holster you can do this at TechShop, but if you are going to use a real pistol, this step is best completed at home.
BEFORE YOU PROCEED: If you are using a real pistol, make sure that it is not loaded, and remove any ammunition from your work area.
Start by cutting a piece of square acrylic rod so that it just fits between the front and rear sights of your pistol. This rod will be used to form a sight channel in the holster, so go ahead and secure it in place with some waterproof tape. If you do not want to get your pistol wet, you can wrap it in cling wrap, but I didn't bother.
Test-fit your pistol in the holster and get a feel for how far into the holster the pistol should sit. It should be pretty loose at this stage. It will tighten up as you work.
Fill your bowl with enough water that you can completely submerge the holster. Use the microwave to heat the water to boiling, then remove it and place the candy thermometer in the water. Let the temperature drop to just below 160 degrees Fahrenheit.
When the water reaches the target temperature, submerge the holster completely and keep it below the surface for forty-five seconds, then withdraw it.
Holding the acrylic rod in place between the sights of the pistol, push the pistol all the way into the holster. This may take significant effort as the leather will have started to shrink.
Once the pistol is situated where you want it in the holster, use your burnishing tools (sharpy, spoon, etc.) to burnish the surface of the leather around the pistol. I start by using my thumb to push some leather into the trigger guard slightly (not enough that it will contact the trigger) and get good definition around the trigger guard and the overall shape of the pistol on both sides of the holster. Then I use the tools to push all of the leather as flat as possible against the pistol, paying special attention to getting creases along the bottom edge of the slide, the ejection port, and the acrylic rod forming the sight channel. I focus most of my attention on the outside of the holster, leaving a general shape on the inside, but trying to get some detail on the outside. As the leather cools and dries it will hold these details, which will help it to hold onto the pistol more effectively. This also helps give the finished holster a nice look. You need to work fast, as the leather is cooling, so get as much detail as you can in five minutes or so.
Insert a stiff belt through the slots of the holster as shown to give some shape to the belt slots and help maintain the holster's curvature.
Let the holster cool for forty minutes with the pistol and belt in place, then remove them and set the holster aside to air dry for twenty-four hours. Avoid the urge to handle it before it is completely dry.
Once the holster is dry you will be surprised at how hard and strong the leather has become.
You're finished. Enjoy your new holster! Once the holster is dry you can use it as is or you can try any number of finishing techniques, buffing with some bees wax and neet's foot oil will give it a really nice shine. I decided to stain mine with a little Fiebings Light Brown. A single light coat gave the holster a really attractive mottled look that you can see in the cover picture.
I hope you've found this instructable informative. If you'd like to see some of the things I make, check out my Etsy store at: http://www.etsy.com/shop/HandmadeByDroids