QGIS How to cut out a state

Question

I don't know anything about QGIS, all I want to do is cut the shape of Missouri into a topography map for the purpose of 3d printing. I'm using the topography data of Missouri and some of the surrounding areas that I got off of OpenTopography and imported into QGIS. I'm following this guide: https://www.instructables.com/3D-Print-a-Custom-Raised-relief-Map/ and want to do it specifically with Missouri. I only need help to cut the map into the shape of Missouri, and this tool is kind of niche, so I'm not really finding much data, especially for my application.

Answer 1

1. First you need to find a vector polygon from Missouri. For example this one from all states.
2. Then you will need to filter only to get the boundaries of Missouri. Therefor use the selection tool (1), click on Missouri (2), right click the layer (3), export (4).
3. In the next dialog select ESRI Shapefile as Format (1) and EPSG:4326 WGS84 as the CRS, because your raster data is also in this Coordinate System (if you are using data from opentopography).
4. Like in this tutorial use Raster -> Extraction -> Clip Raster by Mask Layer
5. Use the raster as Input, the boundaries of Missouri as the Mask Layer and set the nodata values to 0.