Tinkercad is a free three-dimensional editing software (https://www.tinkercad.com). Tinkercad operates on a webpage so there is no need for you to download anything.
The following is a six-part tutorial by PromoAmbitions that will teach you the basics of Tinkercad and how to design 3D objects.
Tinkercad Tutorial Part 1 - (Interface and Movement)
Tinkercad Tutorial Part 2 - (Shape Manipulation and Scaling)
Tinkercad Tutorial Part 3 - (Group, Hole, Align, and Flip Tool)
Tinkercad Tutorial Part 4 – (Workplane, Ruler, Blocks and Bricks)
Tinkercad Tutorial Part 5 - (Circular Patterns and Slicing)
Tinkercad Tutorial Part 6 - (Import Export and Collaborating)
This is a great first start for designing and exporting your projects. If you have any questions email fkail@sarahlawrence.edu.