Model for multiple tables

How do I construct a model to map multiple tables?

For example:

table1, table2, table3

The model will represent a join of table1+table2+table3

I did notice there is a join_table for use. But I don’t want to create
separate models for table1, table2 etc since I will never need to
access them.

Essentially a way to encapsulate the diff tables.