As a person who was actually ignorant enough to go into build season trying to design the robot in sketchup, go with Inventor in Solidworks. Trust me, I can cad stuff in sketchup as fast as I can in Inventor or Solidworks but when you have to change something in the design it becomes a new level of complexity. I ended up scrapping sketchup a week into build season and learned Inventor very fast. Which I can also say that sketchup is really good at helping you get into the "good" cadding software. Inventor and Autodesk take some getting used too but I promise you will grow to like it.
