To do that properly I would have to use websockets but I would have to move mecabricks to a dedicated server... More expensive and more trouble as managing a server is not my domain. To tell you the truth I already thought about this idea 😉

Another idea could be this:
you can open a multiple owner model (if you are allowed to do it) only if no one else has currently opened it.

Yes, this one is probably a bit easier to make.

That would be fun! We could have a relay community build like Eurobricks has with LDD.

ooh that would be nice ive used stud io but prefer mecabricks yup this idea would be nice!

for zanna's idea you could do a 'multibuilder code'

E.G.
you could make a model with another user and pm them for their code
(the code would be a string of 4 numbers and 3 letters e.g. 1234abc)

and once they give you their code you could add them to the project

why not multibricker code? @GavGeist650