The problem with FreeCAD is that the UI is abysmal. There is tons of duplicate functionality in different benches, but if you start in one you might discover that it doesn’t have what you need and have to start over in another.

The trick is to include a wedge in the base of the print, then you don’t need much force. The standard base plate generated by ChiTuBox does have one already.

I question your definition of flat.

I’m always using a plastic spatula, so mine is pristine.

I got this one, but they need some significant sanding, otherwise nothing will stick to them. They’re very cheap with worldwide free shipping, though.

So, pay extra to get the smallest components possible for a desktop PC, and then mount them spread out on a giant wall.