Separate access credentials for shop

I would like to give a customer access credentials (separate username / password) to be able to edit the "simple shop" of the web-site. You should be able to add / edit / delete products with text, price and photos. But I don't want hi to mess around with the design of the web-site or the other pages wich should stay under my control. This would be a real division ob labour between web-design and data entry (for the shop). What do you think about it?