All pillar from 5568 kits broke I searched for 3D printed alternative.
I found Crosslink's and add 30212873.
Both are available in STL or editable Freecad (0.21) model.
I tried to reproduce connectors without success for now.
Feel free to continue trying or add others parts to the tree.
I printed in PLA, layer 0.2, oriented on one edge at 45deg to reduce the use of support without collapsing walls arounds slots/holes. I just activated contour + 4 Pilars of organic support and 0.2mm Quality profile.
The author remixed this model.
Editable Freecad Model added and and add 30212873