If all you need is a single terminal to the Docker image:

$ make interact

If you need a handful (or more?) terminals to the Docker image, you can launch it in a detached state as follows:

$ make start

You can launch as many instances as you'd like. The instance IDs appended, in order, to .instances.

To attach the latest started instance:

$ make attach

Do this from multiple native terminals to achieve the intended "multiple terminals" effect.

If you would like to attach to an instance initiated at a particular depth (since make start may be run ad nauseum), you can set the D (for depth) variable. For instance,

$ make D=2 attach

$ make stop

This will also automatically detach all attached terminals.

OBS! This deletes .instances.