I’ve been using Sketchup for the last few years when it came to 3D design as it’s free and quick to get into but it’s really only useful in drawing what you already have planned in your help. It’s not so good at actually finding a good design. This made me look into other 3D drawing tools and out came Autodesk Inventor.
Inventor has built in tutorials and it is free for 3 years for all teachers and students. Most Autodesk software is. Have a look at what is available here: https://www.autodesk.com/education/free-software/all