Congratulations! I have no skills and could do something. I guess this will help designers to add something different in their pages. I think a kid can play with it and make something nice too.

I'm a founder and technical lead- Feel free to ask me any questions!

is there a way to make parts or joints fixed when bending, so I can't turn my train upside down when I rotate a wheel?

No, but that's already on the list for enhancement in the next point release- I struggled with that because it isn't a strictly necessary feature, but I agree it's needed.

seriously cool, I'll have to give it a try!