You should have check boxes next to people's names when in the factory tab under each chassis of vehicle so that you can pick who and who can't make a certain type of vehicle. Keep the restrict all check box so that you can save res for that shiny new forward base, or that nice research project.
the allocating certain people building rights would be a right farse though, obviously you get people who are just plain stupid but youll get commanders who will deny armour to people new to the game which is: 1) arseholic (the process of acting like an arse) 2) going to stop the community from growing the points based res limit is a fairly good idea in theory but again it will put new people off the game if they cant jump in a tank any time soon all the other ideas people have had (letting people build with a certain amount allocated only to the commander etc) are very good and i would like to see these is the game