To the request of one maker I made the 15 mm diameter, named support (left - right) and clamp (left - right) -(1-2).
The z carriage bends still easily even after there first remix. I extended the legs and moved the part over the profile, just to get more room under the bed.
The bearings were in my first attempt too tight and doesn't roll fluently on the rods. I made a 16 mm room (instead of the 15 mm exact fit), with that slope i put the 2 bearings on the rod, put some hot glue in the rooms and press the Z carriage on all. With that way there is absolutely no slope and the bearings are perfectly aligned on the rod without stiking.
The bed is now much more rigid.
I give you also the CAD file (Fusion 360)
I made it with PLA, thats strong enough for the purpose...