(Open files) Support alu Chain mpcnc remix

Hello, I first printed the original part but the Z axis touched the aluminum profile when it came down so I modified the room from scratch and made some other corrections.

Here is the list of changes made:

- Offset of the piece of 2cm towards the outside so that the z axis can fully fall without being generated by the aluminum profile

- A second "hole" has been added to the part to be able to put the aluminum profile in the direction that we want (towards the inside or the outside)

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