/diy/ - Do It Yourself

Hi /3dpg/ I need some serious advice. Please help me out.

The Situation: My first and only 3D printer (Monoprice Maker Select Plus) is dying. I have been replacing parts and it seems like the more I replace the more breaks. This design has some serious deficits and I am tired of band-aiding it. At times it did make some really amazing prints though.

1. I am trying to start an internet business designing and printing automotive parts. I need to get a workhorse printer that will allow me to prototype and produce really clean low volume parts at 0.1mm layer height. It needs to be good printing PETG all day, and not be a constantly moving target. I have a million other things related to designing parts and trying to start a business that need my attention over fiddling with a temperamental printer. I'm looking at:
>Creality Ender 5 Plus
>CR-6 SE.
Any other recommendations? I would like to get away from bed slingers if possible.

2. I was able to print functional and strong 32TPI threads with my Maker Select Plus before it really started going south. I would like to disassemble it and DIY together a new high accuracy printer for doing 140mm and smaller parts. Precision and repeatability are the objective, speed is a distant second. Any ideas what a good design/kinematics would be?