Y dual linear rail mount - ender3pro/v2/Max - MGN12H

Update: installed on my machine and it works great!
(I uploaded new alignment tools as the top mounted rail model were too long for this.)

Stock Y endstop switch can stay in place (at least on ender3v2), and should activate at roughly the same Y position as stock setup.

may not work on ender3 v1 (due to the slimmer Y extrusion profile)

• use 300mm rail (320 might work too)
• Due to the linear rail interference you will need M5x12, as stock screws are longer (I got this set, https://www.amazon.com/dp/B0734NVR48 which has some M5, M4 and M3)
• Due to the heat of the bed higher temp material is recommended. Would avoid PLA if possible. If doing PLA, I recommend printing a backup set in case it deforms
• Ender3/pro/v2 and similar 4 mounting holes - print two of "ender3_dual_Y_rail.stl" (NOT 3_max)
• Ender3Max & similar large bed 6 holes creality platform - for the 3max I recommend printing two "ender3_max_dual_Y_rail.stl" (not the mirrored) so that the rail block, is closer to the front one side, and closer to the back on the other side, for more stability. If interested can very easily make a 2x MGN12H block per rail.
  If using a normal and a mirrored, both rail block will either be on the front or the back.

Installation:

• Print a few alignment tools, I recommend PETG as it can bend a bit without breaking, PLA is very stiff, and breaks easily if bent a tiny bit, but should still be usable.
• Print two of the parts for your printer, they are symmetrical.
• disable your printer bed
• place the alignement tool on the rail before you install it, as they are tight, and might break when you remove them.
• mount the rails closer to the top, use M3x8, m3 t-nuts and and the alignment tool
• center the rail, leaving roughly a 10mm gap on each end.
• Add the M5 hex nut, temporary screw in an M5 bolts in each hole to grab and lift the nuts, as they are in the way of the rail initially.
• mount the printed part on the rail bocks, and secure it with M3x6
• you can now remove the temporary M5 bolt
• place the bed platform and put the M5X12 bolts and secure - NOT the stock M5  they are too long
• finish assembling the bed as normal.

The bed was only raised by 2mm from stock so stock belt attachment works
min and max Y.

If the alignement tool is too hard to use let me know and I can figure something out.
or feel free to tweak it, step file included. I added a "maybe easier" model, but it might not grab as well.