Original-Prusa-i3 VS Ender-3

I've been effective with OpenSCAD and FreeCAD.

OpenSCAD is good for enclosures: https://github.com/sbambach/MarksEnclosureHelper

and mechanical systems: https://github.com/prusa3d/Original-Prusa-i3

Don't think of it as a programming language; that will hurt you. Think of it as a specification language. That helped me.

Being the printer already assembled and working, I am looking at pg. 12 of the printer manual downloadable from prusa3d.com, chapter 6.3.1 Calibration flow and wizard, showing two different scenario... one for kit and one for assembled printers. Am I correct assuming I can just go through the latter? Also it's not very clear to me if that's the process I have to go through each time I turn the machine on, before attempting any print.

TLDR: replace the adapter-printer if it's worn.

They’re usually bought at https://prusa3d.com

On top of that, people simply don't know what they're doing. For example, the Prusa MK3S+ STL files are licensed under GPLv2, which does not make sense because there is no source (the source files are GPLv3 for some reason). But if you look at the remixes, the majority are licensed under some Creative Commons license end even the Public Domain. All those remixes are mis-licensed because only the GPL is compatible with the GPL.

you are right, but many people have asked for this.... reddit, github.. even on prusa3d.com but they dont care...

The BOM (of sorts) of the MK3S exists here.

No corresponding source for the parts is available? I don't seen an MK4 branch in there, unless they ditched openscad entirely (even then at least STEP files should be provided if it's still Open Hardware).

Original-Prusa-i3/extruder-body.stl at MK3S · prusa3d/Original-Prusa-i3 · GitHub

From prusa3d.com:

If they have been released, they will be on GitHub. You may find that latest revisions are absent.

They aren't ripping of without giving back. You can go to GitHub rn and download all files for the Ender 3 and CR-10 etc licensed with GPL3. That is also the reason you find, that pretty much every budget printer looks like a Ender 3 these days. Creality really isn't a company that only takes, they also give back to the community.

There should be everything you need on GitHub. https://github.com/Creality3DPrinting/Ender-3

As for it not being open source, here’s a GitHub link with everything you need.

Creality also open-sourced the Ender 3. I'm on mobile so can't handle most of the file types but their repo at https://github.com/Creality3DPrinting/Ender-3 may have the info OP needs.