I just finished my first concealment holster for a friend at work. I used a Food Saver vacuum bag. I put the pistol between two pieces of cased leather, then put a paper towel on each side to absorb some of the moisture, and to prevent the texture from the inside of the bag from imprinting on to the cased leater. This I figured out after a failed attempt. It worked perfectly! In seconds the leather pulled down onto the pistol. I tried it with a kife and of course, it worked just as well.
Of course the leather will not dry inside the sealed bag, so I left it set for about 20 - 30 minutes before I cut it open and layed the pieces out to dry. The machine I used was a borrowed one, but they can be bought for under $100. I'll be buying my own soon.