The most iconic machine in the space what created by human is the satellit, so i made a satellite keyholder in tinkercad. That was the first time i used tinkercad and wondered how it is easy to use and user-friendly.
Check the steps about the creating and i hope you like it.
Step 1: Base Structure
For base component i combined a cube and a cilinder because it is some more uncommon. So first step get yourself a cilinder what you split from four sides with cubes.
Step 2: Solar Panel
In this step i made the "wing". You can use copy and paste in every part, so you dont have to make same part again. I made only one solar panel because it will be a keyholder and it will be much longer with second panel.
Make some pattern with cutting.
Step 3: Basic Model
So use copy and paste and rotate it and fit to the other side of the model. Now you have the basic satellite model.
Step 4: Top
Use group command to the wings to move them in group and rotate it in 30 degree. After that you should make a new plane for better positioning. Create the top with the same technic like basic shape and pozition it with align.
Step 5: Keyring
Last but one you should make the keyholder ring. I have created it from a ring and a cube, and set in the right position with align.
Step 6: Patterns
Last step you can make some patterns. 3D printing most probably can be made by one color but it will have a good looking with patterns. Don't forget you can use copy and paste and group command what will help to rotate, move, positioning and sizing the parts together. Make on it some extruded parts, cutted place.