Next, come up with something you want to model. If you picked something complex I would suggest you just pick one part of the completed object. Let me use an example, say you wanted to model a new type of mountain racing bike. In that case, you might select to model the front wheel as a place to start. If you can’t think of something to design just use an object around you and design a model of that object.
I like to take the next step to put my idea down on paper. This is optional of course but I find that it helps me think through the problems of the design and consider measurements, materials, and important details of the shape.
This is also a good time to start an engineering journal of your effort. As you work on the design you will run into a problem that must be solved. You will have an idea for another part of the design. You will find a source for information that you will require more of your time but it is a distraction from the task you are working on. These kinds of items go into your journal so you can focus on the current task. Don’t worry if the design you are working on is very simple you will need to make notes about what you learned about your first attempt.
Now attempt to model your first design using the CAD tool you selected. Keep in mind that you learn more from mistakes than an easy success. Anything new is full of places that will trip you up. These are the same challenges everyone has to learn. If a challenge just seems too hard, ask someone with a bit more knowledge and experience using the tool you are using for help.
Once you have a completed design it may be fun to use a 3D print service to make a physical model of your design. Most of the tools below provide some initial help in working with 3d printers.
This could be the start of something amazing. Good Luck.
This is the fastest way to build 3D CAD designs I have ever seen!
Another tool is very impressive and it looks to be “free” for use.
You should also check out fusion 360 for hobbyists (from autocad)
For surface modeling, look at https://www.blender.org/
This is a very different tool than the others on this list.