A TM1 Sandbox is a functionality related to the IBM Cognos TM1 solution. Sandboxes are versions of cube views saved locally. This feature allows users to have their own personal workspace with a personal copy of the data on which they can do simulations. The sandbox feature can be disabled or enabled by adding a line in the TM1s.cfg file.
It is possible to create sandboxes in the different TM1 client applications. Those sandboxes however cannot be shared among the applications. For instance, a sandbox created in TM1 Web is not visible in TM1 Contributor.