Corridor81

Tomasz cwik corridor81
Tomasz cwik some steps
Tomasz cwik corridor2 sk
Tomasz cwik corridor3
Tomasz cwik cor sk

Personal project
...
checked
https://blenderartists.org/forum/showthread.php?381665-GroupPro-add-on-for-working-with-group-instances-(commercial)
https://extensions.sketchup.com/en/user/6256/store
https://extensions.sketchup.com/en/content/vertex-tools
and more..