Arrived here by following links regarding door lock systems.
Have read some comments and viewed an online video demonstrating a HackSpace door lock project. The following, or a system offering parallel functionality may already be integrated with what some of what your participants/members are doing.
Could submit some history, but that would open door for "get to the point" complaints.
The point: It is possible to combine what some of your participants have done (usb key door lock system) with some software (java or c++ program) to create a lock system that could be applied to home key systems, business key systems, car key systems in a way the keeps costs to a minimum and significantly empowers the owner/manager of the key lock system. For example, a car owner could use the system to change all keys for her/his car at any time/place he/she may want. No other key in the world would open that lock. It would also be possible to have unique keys, for unique owners, all of which would work with a specific lock. An associate database would record key use, filtering on factors time period use sensitivity factors. A brief description can be viewed after the $$$$$ signs at:
I'm not selling anything. Anyone can have the dabble of associate code. Many programmers can write much better code.
This project can be applied to any object and the objects associate functionality.
Nuff for now.