Completing your design Once satisfied with your design surface and/or drain.  1. Select the ' Return ' button . (Top right corner)  2. Select ' Yes ' to keep the design surface.  3. Select the ' Save proj. ' button to save the T3RRA project. Once you have finished making all your design changes, move onto step 4.  4. Select the ' Apply ' button and follow on screen steps to begin implementing your design.