Free 3D drawing software

[rocketlily]

I've been taking a look at some of the free 3D software that can be downloaded. I am not a professional user of this type of software, but when I spend the time doing some I like it to be right.

Sketchup: Looks easy to use, but I don't think it can be converted to PDF or used by any other programs. I don't know if you can share your work with anyone who doesn't have Sketchup.

Alibre: The drawback I see with this one is that color rendering is only available for those who have purchased the professional package.

Are there any programs that you have downloaded for free that you are happy with?