How to extract cells that are attached to selected surface?

Hi, may I ask if it’s possible to extract cells that are attached to selected surfaces? Like extract all boundary cells of a model.
Asking as I want to create a figure that boundary cells and interior cells have difference color.

Welcome to the ParaView Community @javen!

You can indeed select all surface cells you want to extract by using ParaView’s Selection facilities. You’ll want to select cells by clicking the image button. You can add further cell selections by enabling the image button and making more cell selections. For example, if you want to select all surface cells, you’ll probably need to make several selections, rotating about the scene and making additional cell selections until all cells are selected.

Next, use the Extract Selection filter to extract these cells. That should get you the result you are looking for.