EDIT1: Fixed the files, i uploaded an old version. Now it is the right version of the file
EDIT2: Improvement for overhangs and tollerances soon.
EDIT3: Improvement for overhangs and tollerances relased
UPDATE 4: Release a model for easy X check pass with prusa firmware. So you can use this conversion with stock firmware and einsy board (NOT FOR MK4)

IMPORTANT EDIT 4: The Z axis top needed some adjustment. I uploaded the new version for the Top.
The STEP file needs to be uploaded yet, i'm just waiting the complete version for a compendium of the total of the mods i used/designed/remixed.

IMPORTANT EDIT 5: mod tested and works now, the previous versions had some little problems, now fixed. I Will release a compendium soon. The compendium will have some mods specifically for duet. I'm working on the carriage to improve the part for sensorless homing. Stay tuned. Some asked me why duet. Well i'll give a short answer for now, later i will give a more specific answer. 1)you will have most of the relevant innovation offered by the mk4, Input shaping (and the Accelerometer, Adafruit, Is supported and has a specific plugin) ,Preassure Advance, fast and reliable webui with macros , plugin, support for camera etc. 2) Better driver then mk4, the TMC 2660 Is a lot stronger then 2130 and you can use the LDO 0.9° without any temps trouble. 3) you can purchase a good quality clone of duet 2 wifi from bigtreetech, for 80 dollars you have board, cables and paneldue also. 4)why not? Try something different.

At the moment i reworked the STL of the MK4 to fit with 8mm rods and with 2x LM8UU (so u can use the LM8UU u have in ur mk3). I reworked the X parts to fit with an MGN12 350mm and a MGN12H. It can be used with the mod released for the mk3s https://www.printables.com/model/16838-prusa-mk3-mk3s-mk3s-x-axis-linear-rail-guide-upgra/files
You can use from this mod the standard carriage parts, or the “special” for bondtech or Zorbiter, depends on the extruder you would like to use.
I'm working on a conversion with this parts for Zorbiter and a Duet 2 WiFi. Probably i will add the rework for the board and the config files when i will test properly the conversion.
In the meantime if someone would have fun to test the first part on his mk3s, or would work with the step file, well, here it is