Science Buddies: "Ask an Expert"

Hi,
I am currently doing a project on the effects of different turbines on the production of energy through wave power. I got in contact with a mentor who suggested that I prepare some designs before our meeting on August 25th. He suggested that I use the software tool SolidWorks but I did not understand which programs I should download. I really need advice and help because I don't have any experience in using online design programs. Last year, I made my own makeshift generator, but I would like to improve on the design and hopefully advance further in science fair this year.
I need recommendations for easy to use design softwares where I could create some examples of what I want my generator to look like.

Thank you.

Most of these tools are pretty complicated. I've tried using them before but they're kind of like photoshop... easy to do simple things in, but hard to to much more than that without a lot of practice.

That said, SolidWorks has a good reputation among the mechanical design folks I hang out with. The only issue would be that it's not free. Even the student edition is $150 (see here: https://store.solidworks.com/studentstore/default.php).

The only thing I know of that's free is SketchUp: www.sketchup.com/. I don't know that much about it, though... I tried using it several years ago when it was (I believe) a free tool from Google, but it was pretty basic back then.