Have you seen the 100 numbers task?
I use it at the beginning of the year, follow it to a T, and then reflect with the kids about what makes group work so great and what it looks like. Then I post pictures of them working and their contract for it on the wall. That’s our pillar.
I also just wrote a grant for a classroom set of mobile whiteboards (only about $200?). Have you seen the research for “vertical non-permanent surfaces”? That also really helps with the collaboration.
I found that giving students jobs SUCKS, and instead I create small (3 person groups) and encourage all to participate (some with rules on HOW to participate, like the VNPS).
I think having tasks in the beginning and throughout the year which have NOTHING to do with math and EVERYTHING to do with teamwork helps.
Also, doing daily random seating helps with that. I know that there are cards circulating around for that, but then the kids trade them. So I use the app “Team Shake” to help with that.