Minimize free space

Hello

I've got a dataset that is static, so I'd like to store it in a tablespace/datafile with as little free space as possible - none would be optimal. 

I've tried several methods to achieve this, but the best i've been able to squeeze it down to is ~300MB (using dba_free_space to determine this). 

The dataset is roughly 30GB of tables and indexes, so we're talking about a very small amount of free-space in reference to what is in the datafile, but

there will eventually be thousands of datasets, so I'd like to minimize the extra space usage.