Pretty simple. Allow us to easily share links to our creations.
If you need a model for how to do this, take a look at tinkercad.com. Make something and then click the person icon in the top-right. This will generate a link that can be shared with that person, sent over email, whatever.
And allow to optionally include some of the viewing state (active scene or camera position/orientation) as URL parameters, like the start time on youtube.