I swear there used to be one somewhere, but here’s the thing.
It would be a tool, where you designate an object as the “center of gravity.” I don’t know if such a thing is actually possible, so I’m thinking it would merely just be “select a thing for everything to revolve around.” You could set the radius in the tool menu, where the “gravitational force” will affect certain objects . It might just be like faux gravity, although a directional gravity tool that also has options for a circular orbit would be really cool.
You might also select certain objects to revolve around the central object, and maybe even the number of orbits (for example, 5 orbits means that 5 objects can be attracted and bound by gravitational pull.)
I have no idea why I’d like this addon, to be honest although I could see this useful for contraptions, dioramas, and spacebuild applications. The science teachers using GMod could also do atomic structure using blue barrels as an electron, a giant sphere for a nucleus, and so forth. I think physics in Gmod gives me a hardon or something. :V