Pre-industrial workers had a shorter workweek than today's (1991)

I did try to answer one of your questions: the machines are serviced by the members of the collective. In any plan for a society education must be considered. But much the same way that any halfway technical person can learn how to fix a 3D printer, these machines should be designed with repair in mind and along with open source designs there would be freely accessible repair guides.

Production should be somewhat decentralized so there should be many places manufacturing motors etc. but when it comes to putting the machines together I’d expect that different collectives would focus on certain machines and they would trade with people near them. Remember that you can always fall back on “people use money to exchange goods and services” I’m just imagining a model where that isn’t really the dominant way people manage their day to day survival.

I am not sure that decentralization is less efficient.

Getting the raw materials is one of the more serious questions. Generally falling back on non-automated things, firms should be cooperatively run. Also raw material consumption would arguably go down for westerners who move to this model, as there would be minimal waste and the machines would all be designed for repair.

Health care is to me essential but these things would vary from region to region based on cultural ideals and material conditions.

I am an engineer and I love to fix machines. I would rather spend my days fixing machines than working a corporate job to enrich a few executives. People who want to be Doctors or teachers often feel similarly. They need their material needs covered so they can do what they value most - helping others. I basically just think we can really streamline the whole production side of the economy and design things so everyone benefits and actually stops needing to work 40+ hours a week forever.

Seems like you want to take freedom of association away from the rest of humanity and put it into your own hands. It's hard for me to imagine a mentality that is more self-centered and more selfish than that.

Aside from that is the matter of physical characteristics. I am over 6 feet, naturally scrawny but bulky due to lots of strength training. There are many jobs in which I would not last because my body is not made for it.

One of the worst jobs I ever had was making concrete walls that would be shipped around the west to make big buildings. We were working at a windy area, which would sometimes blow the walls around when moving etc. People died every now and then when accidents happened and they would get crushed by a wall. It was cold and physically grueling, much of the workforce were illegal immigrants who would call in sick almost once per week. At one point a foreman told me how much he appreciated how much I showed up for work - I was calling in sick once per month because I couldn't take it.

There was guy there who had been doing the work for 20+ years, he was in astounding shape. He was probably 5 feet tall, extremely wiry, and could walk along a thin concrete wall hanging 20 feet up in the air by two chains without hesitation and if need be walk onto another wall, pick up a tool, turn around and walk onto the hanging one to do something. We would watch him in awe of his abilities. But of course he had done 20+ years of training for this, and had the body type that made him a perfect fit for the job. The other guys who had been there for 20 years worked as hard as him, but they were less well suited to the job than he was.