PrivateArea is a module developed by Custom Scriptz for Zen Cart where Manufacturers (often called Designers by Scrapbooking Stores) will have it's own area where they can individually manage Products, Coupons, Sales, Special prices and more, withow accessing other Manufacturers stuff.

Features: http://customscriptz.com/wiki/PrivateArea#Features
System Requeriments: http://customscriptz.com/wiki/PrivateArea#System_Requirements
Screenshots: http://customscriptz.com/wiki/PrivateArea#Screenshots

Note: This module has been tested and works fine with no moded version of Zen Cart v1.3.8a and above. Older versions might work, but if not, you will have to upgrade your installation.