Shapesmith. I have been wanting something I could recommend to people as heartily as I recommended Tinkercad before they went subscription based. Is Shapesmith that service? No. But it could be. Shapesmith is in early beta at the moment and is better suited for the draftsman than the tinkerer because it's going to take a little while running through the tutorials before you'll be able to make your first chess piece, which has somehow become the hello world of 3D printing.
It's still in early beta and very buggy. I noticed on my computer whatever I wanted to select I needed to click to the right of. But it's also in development so it's likely these things will be fixed.
So check out Shapesmith, sign up for an account, and let's see where this is going.