Stage 3. Cubby hole sides going in. Spirit level is there for a purpose (ie. said item and David are joined at the hip. As for me - if it looks level, it probably is.....)
Stage 4. More cubby hole sides.
And "Eureka!" he said. It's level!
Stage 5. View from other end. Note the drawers (or the spaces where the drawers are going) - perfect for fat quarters!
Stage 6. Shelf supports in place and timber on top ready to brace everything before the top goes on.
And it's still level!