Geeetech A30 X MGN12H Linear rail mod (A10 A10M)

I designed all for using with my petsfang and original carriage. My carriage has a big hole in the middle (v3.3 A30). So I couldn't just drill it

You need a 400mm MGN12H rail + block. You can use original belt:
http://s.click.aliexpress.com/e/MGvlppuk

It should works with A10 and A10M too. Please confirm me if You try it.
A10 and A10M require a 300m guide: http://s.click.aliexpress.com/e/_srmsaq

There are 3 solutions:
A - that one I used and tested. It is composed by original carriage + printed plate + modified Petsfang + X endstop
B - just full cage for using without original plate. With this solution, I didn't design the X endstop. (You could try this support https://www.thingiverse.com/thing:3094482) I didn't test it
C - plate for using with original carriage and original cage + X endstop. You can use this plate just for drill too. I didn't test it

With A and C solutions it is not essential but recommended to print belt spacers, so the belt is perfectly aligned. In this case You have to print X_motor_spacer for endstop. Probably You need a longer belt. I don't know because I changed the belt anyway with a stronger and better one.

For endstop, if You think to modify the Z axes with MGN12H too, You could install X motor support with endstop directly. It is here:
https://www.thingiverse.com/thing:4059835

You need 4x M3 screws for MGN12H block and 3 or 4 M3 screws + M3 T-nuts for rail

http://s.click.aliexpress.com/e/2B6eKbYy

http://s.click.aliexpress.com/e/qsa9Hg2c

I printed all in PETG with 100% infill. You need supports just for petsfang

For a for a precise installation of rail, You can use this guide
https://www.thingiverse.com/thing:2152669

Here a demo video:
https://youtu.be/vFeug0_gQI4