It isn’t the copper swarf you need to worry about - it is the fiberglass dust! Seriously, a painter’s mask will not save you from it. It also requires carbide bits and will wear them.
If you can stand to use phenolic PCBs and can find a source, I’d suggest at least starting with them.
Our makerspace, OlyMEGA, was given a Shapeoko 2 back when they were giving one away to a makerspace in every state. As expected, everyone was excited to assemble the kit, but lost interest when it got to aligning and getting it actually working.
So I found it sitting on a table, covered in stuff. I found most of the bolts were loose. I took it home to make a torsion box base for it, tighten and align everything. I swear, that is all I was going to do…
A year later, it has the torsion box base. Which sits in a box with the electronics and power supplies, with a pullout tray for a laptop. Cable chains everywhere. Upgraded Z axis, upgraded motor with speed control. Dust cover. Someone else said they were going to install a dust capture system, but that hasn’t happened and it has been another year.
I don’t know if you can see this: https://www.facebook.com/pg/olymega1/photos/?tab=album&album_id=1033826970037988