The cross-section feature is a powerful tool that allows the participants to easy cut the model, this tool is used for cutting into the model to get a better view of whats inside of the models, and it makes it easier to see the different elements like the floor planing etc. 

Press the right grip button -> Hold to move and release to lock -> Press the right grip button once more, if you would like to erase the cut. 

You can measure lengths between your controllers. 

Press and hold the left grip button -> Review and measure lengths