Most holster making is done using "dummy guns", cast replicas of the originals. Two or three sources produce dummies, but typically only for current production handguns having large market shares. Many handguns never result in dummies, and new handgun models may be on the market for a year or more before dummies might become available.
The alternative for holster makers is to purchase the actual handguns. This would require a steady demand for holsters to justify the expense.
An alternative for owners of other handguns is to provide the handgun to the holster maker for patterning and forming the holster. Some states have restrictions on transfers of firearms that may apply. Shipment across state lines would be subject to the Gun Control Act of 1968, and expenses can run up quickly for shipping charges and FFL transfer fees.
The best possible option would be to locate a holster maker close to your residence, and certainly within your home state. Even then some caution is called for to make sure state and local laws are complied with, security of the weapon and insurance coverage are adequate, etc.
Best regards.
