# Cap open boundaries The **Cap Open Boundaries** tool fills open holes in geometry by generating new faces along the boundary edges, ensuring a closed mesh. #### How it works * Select an open boundary (hotkey `O`) * Press **`Ctrl+O`** to activate the tool * A new face is automatically created, capping the selected boundary {% embed url="" %} #### Use Cases * Closing gaps in a mesh to prepare it for further modeling. * Ensuring a watertight mesh. * Simplifying manual face creation by automatically generating a cap over open boundaries. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://help.vectary.com/documentation/design-process/edit-mode/cap-open-boundaries.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.