How to structure a database?

We have just installed Oracle 8i on a AIX 4.3.2 server, and are now considering how to structure our database.

We have about 60 users who will be using an application that interacts with Oracle. Those usere are assigned to a number of projects, and can freely switch between those projects, which they have been granted access to. Projects vary from lasting a few days to several years. Each project will typically hold between 3 to 10 tables of data of only a few thousand records.

As I'm new to Oracle (but learning fast), I'm trying to figure out, what would be the best way to map this situation, into Oracle - Schemas, Users, Roles, Tablespaces.

I would like to have each project reside in it's own tablespace, and create a role for the ~60 users that will be accessing those projects. A user assigned to a project would never be allowed to create tables, but should be allowed to create, update and delete records in tables created by our development department.

In order to implement this, I'm unsure of how to structure this within Oracle. Could some kind soul please enlighten me of how to structure this, and a short explanation on the steps involved - that would really help - thanks!

PS: What confuses me, is the fact that tables are created

    within Schema's and tablespaces, which in turn are     user-assigned not project-related!?

+---------------------------------------------------+

| Schema: PROD                                      |
|                                                   |
|                +--------------+                   |
|                | Role: USER   |                   |
|                +-------+------+                   |
|                        |                          |
|         +--------------+--------------+           |
|         |              |              |           |
|   +-----V-----+ +------V-----+ +------V-----+     |
|   |Project: A | | Project: B | | Project: C |     |
|   |Tblspace: A| | Tblspace: B| | Tblspace: C|     |
|   +-----------+ +------------+ +------------+     |
|                                                   |


+---------------------------------------------------+