For years now our team has given out the First modeling software in the fall and asked a couple of team members to get up to speed in them with the hope of designing and modeling our robot with them. Every year this has been a failure . We never had any students become proficient enough to do it. This year once again no student was able to take advantage of the provided software. I was very surprised this year when I received a PDF email from some team members, after our first design meeting, of a full 3D model robot. I was stunned. At the next meeting, I found that the students tried google sketch up and with about 2 to 3 hours of practice had become proficient enough to render the ideas we had discussed in the first meeting.
I know that google sketch up is primitive, but I am impressed with the results. To see a group of 8 students hovering around the projector designing a robot for me as a mentor is very rewarding. So if any teams are like our team - try sketch up. Are any other teams using it?
I agree with you about the use of inventor being hard to learn in some cases, I’ve taught myself about electronics, HTML, PHP, a bit of C, and Solidworks, but inventor evaded my abilities.
We’ve used sketch up before on a few things, but found that a few hours of Solidworks training gave us about the same result, and Solidworks works very well for our team.
I swear by Solidworks and love using it, I taught myself in a few hours how to make basic parts and the rest just came with experimenting.
I know Solidworks offers free Student versions to teams if you want the link I’ll try to hunt it down.
I have been using Sketchup for a few years now, and the other day I made a mock up of a part on our robot in <30 seconds it seems like. While machine shops won’t accept the files (the machines that take computer files won’t take it(as far I know)) it is a great way to get ideas in 3d, as you know. A few other kids on 1793 have tried it, and have gotten alright at it, to where you can tell whats going on, and thats what counts.
Another thing to look into is sketchyphysics, a plugin with a basic physics engine so you can get some basic driving or moving whatevers.
Here’s what I’ve done: http://sketchup.google.com/3dwarehouse/search?viewer=15910679408086173567&scoring=m
P.S. look at my signature (fourth one on the left)
No need for anyone to laugh.
We use it all the time for MORT and in class.
btw 104, we stole one of your old members! 
His skills he gained on your team were awesome, better than most of our students. Kudos.