OnShape is my go-to. It's what I taught my students when I was a TA for an introductory engineering class at college, and they could pick it up in about a day.
Can do just about anything a "professional" cad suite does, but it's free, works in a browser, and is generally so much better designed so you don't have to fight against the UI to get anything done.
You were into Warhammer at age 4? Man, I couldn't even read.
The way I picture this is by letting communities have some sort of "partner communities" listing. If mods of games@xyz decide they like the content of games@abc, and gaming@123, they add those communities as "partners" (perhaps those communities have to accept which in turn adds games@abc as their partner). Then, when any user subscribes to one partnered community, they also become subscribed by proxy to the others, and begin to see posts from all 3.
This helps smaller communities piggyback on the success of willing larger communities and gain a bit of visibility as well, which should encourage growth of each partner so smaller ones don't just die out.
Communities can "unpartner" at any time, in which case users would only remain subscribed to the one they originally selected. And of course, users could explicitly block any of the partnered communities if they don't want to see the whole set.
Why plastic washers instead of springs? Is the bed sagging due to the washers deforming with heat?
Wait so what was the trick to save time and filament? Just rotating the part to use fewer supports?
Defederation blocks communication both ways, I believe.