How can I give project permissions for copy only (but more for other projects)?

Ok, I've already done that but I'm not sure if I give access to my master project that people can only copy that project (make no other changes) and then make changes to their new project.  Am I still not being very clear? :) ... please let me know.



Here's the scenario:  I've created a master project and I want my users to be able to copy this project to create a new one.  I don't want them to be able to do anything else in the master project (read is ok) - but I then want them to be able to update their new project... doesnt seem like I can do this...