Is the sandbox still available?

Yes, the sandbox is still available although the way to find it is a bit different.  The direct URL is: https://jazz.net/products/sandbox/   You can navigate to the sandbox by opening one of the product pages for one of the CLM products, for example:  https://jazz.net/products/rational-team-concert/  In the upper right of the product page you'll find a button with the label "Try the sandbox."

I also want to remind everyone that there is a new and improved JazzHub available - check out:  https://hub.jazz.net/   JazzHub no longer requires a project creation code to create a project.  JazzHub is still intended for academic use.