Hello, Airstone Labs!
http://airstonelabs.com/press/announcing-airstone
No more Tinkercad 
Yeah I was pretty disappointed to hear this since I’ve started teaching elementary students using Tinkercad. I’m hoping they plan (or can be convinced to) open-source the product since they are no longer interested in pursuing it.
They are not open-sourcing it. Here’s the FAQ: http://blog.tinkercad.com/faqs/
I had just really chosen to go with them as my Design tool.
snief
I have been honing my skills in Tinkercad lately and am pretty upset about this as well because I was building a course based on it for our local STEM group for the high school… Sucks…
I’m chatting with their CEO on Twitter and trying to talk him into opening it up, wish me luck 
gimme your nick, i’ll chip in
@jasonbot2000 :). I’m volunteering to port it but that’s where the conversation ended 
Open source wouldn’t work, it is built to run with a supercomputer as the back end. I don’t know how much power is needed to run a single instance, but it was created as a service rather than a desktop app. Also the core of Tinkercad is the core of the new product so it doesn’t make much sense for them to open it up.
There’s plenty of open-source HPC options available, without more details I doubt there’s anything in there which couldn’t be replaced with something else (or something new). I could be wrong, but until I see the parts around the secret sauce I’m not going to believe its irreplaceable.