Z-axis motor support

#Z-axis motor support

I've designed it for my Alfawise U30 (Longer LK2 clone) to be able to place a damper on it, and correct the bad piece I've received (a bit twisted). It also rigidify the printer structure, and can be used (I suppose) with other printers.

Beware, this is a bit difficult to mount, and I recommend to use [this kind of things](https://www.thingiverse.com/thing:3050607) with, but once mounter it's very solid and will not move.

You can use those pieces with it:
* [Combined Z-top and Filament guide](https://www.thingiverse.com/thing:3690354)
* [Thin Z-coupler](https://www.thingiverse.com/thing:3690334)