Align two faces without math I'm a complete beginner in Blender (altough I'm quite experienced in CAD use) and I'm trying to build an complex object starting from two solid bodies.
This's the current placement.



What I want to do now is to merge the three bodies into a single one joining them by the facing surfaces without any deformation. The objects are already aligned on X an Z axis I just need to join them. I bet there's a way to do this without having to calculate the offset. There's probably a way to select surfaces to align/match and let Blender do the hard work. I looked around but I found only examples to join surfaces by creating another set of faces or trough deformation of existing faces. Once aligned I would like to merge bodies to have just one single item in scene hierarchy.

-- EDIT -- 

BTW the result solid shoud be this one:
In the 3D viewports menu bar, enable snapping by click the Magnet Icon. Next to the icon, in the snapping to dropdown menu. Select Face, since you want to snap to a face and choose Active.



By moving an object in object mode you can snap its origin to other faces. Go into edit mode &#8633; Tab, go into face mode 3. Select the face which you want to snap (it gets highlighted as the active face) and add all other faces which you want to move to the selection. (Box Select or A)

Press G to move the geometry and by hovering over the face of the other object with mouse, the face snaps to it. Press X during the G operation to constrain the movement to the X-Axis.





If you want to automatically modify the orientation while snapping to an oblique face, check Align Rotation to Target in the snapping settings.



The position the objects center at the face you wish to snap and snap it in object mode.