I think that mod.io would be a good solution for this, as mentioned by Minotorious We can integrate it directly into the game, so people can easily download new plugins/blueprints etc.
Having a custom solution for this would be indeed better (as it would give us full control over this), but unfortunately there would be a lot of work involved to set up a proper website, API etc. and to moderate it... so I guess it's easier to rely on mod.io for this.
There was a discussion about support for Steam Workshop, mod.io etc. in the past in our Steam forum: https://steamcommunity.com/app…ns/0/3123802224166721327/
Some people there would prefer support for Steam Workshop, but unfortunately that's not a perfect solution (as it wouldn't work for non-Steam versions of the game)... but apparently there was no real argument against mod.io either