Thanks @Geo! Your answer is well detailed and easy to understand for a beginner. I wish this was my model but it is something I found in the warehouse. I’m trying to draw a mould that will allow me to cast this part in metal for a foundry project. I found this thread on the subject: Need to create an inverse or shell of a 3D surface but I would also be interested in anything you might have to add that could help me achieve my goal as smoothly as possible.
Thank you for your help.