Enclosure Design Sites

Are their any free online apps/sites that can be used to design custom enclosures for a project. I cant download/install anything at the moment.

Like this one?
http://www.protocasedesigner.com/
“Free Downloadable 3D Enclosure Design Software”

Thanks CrossRoads, I'll bookmark it for later. However, i am currently unable to install/download anything.

Online, I know of none.

I use Sketchup Make on my PC. http://www.sketchup.com/?gclid=CJafgdH888YCFY6EaQodpiMAMQ

I can't find anything that runs online. Would be terribly slow anyway. Ever tried something simple like Google docs? Just text files or spreadsheets, runs too slow to be usable. Designing more complex stuff would be even worse.

I've just found Tinkercad.com

I'm not sure how it compares to some other things. Does anyone have any experience with tinkercad? What are its limitations? Ideal use cases?