I want to flatten the base of my STL file & cut it into a regular shape (e.g., round, square...).
The results I expected should be the same as this video shows (https://www.youtube.com/watch?v=bSNy9iUqDbI). I tried but I did not succeed with his method in blender.
If anyone can help me, I would be appreciated. It is best to give a detailed method because I am a beginner in this. Thank you in advance.
My STL file is here: https://www.dropbox.com/s/by7fdw49x05savj/terrain_test01.stl?dl=0.