In short, Mario characters/items designed in a way in which it would make sense if it was 3D rather than 2D. (Note: this is my take on how I saw these characters in 3D, Feel free to change it up a little bit to your preference).
As a student in Mrs.Berbawy's Intro to Engineering Design class, I decided to re-create some of the classic Super Mario Bros 3 "characters" or icons. In the end, I decided on Mario, and 3 power-ups, the fire flower, star, and iconic mushroom.
Step 1: The Idea
The first thing that you want to do, is imagine what you would like to create, whether it is a character, a power-up, or a scene. After deciding on what you would like to create, try and find an image to either base this project off of, or to try and mimic to your liking.
Step 2: The ___
Now that you have an idea of what you would like to recreate, you can now go to Autodesk Inventor and start creating it. (I would suggest you make yourself a grid to make the entire process easier on yourself).
Step 3: The Extrusions
Now that you are CADing your newfound friend, extrude them so that each layer is extruded a smidge higher than the last one, this adds depth to the print. (You don't need to do this, but it makes the print "pop out" more).
Step 4: Print
Now that you have your little friend, go ahead and 3D-print them out!
Step 5: Vinal Stickers (optional)
If you want to go the extra mile and add colors to your project, you can vinal-cut stickers of varying colors to match your print and give it that completed look.