This ITX case uses 4 Makerbeam XL 15x15x300mm as the main structure.
I Printed everything in PLA and it's not been an issue.
All parts fit on a 256x256x256mm. (P1P)
As the project evolves I will post more.
version 2: https://www.printables.com/model/1122597-itx-pc-case-v2
Honorable mentions:
I got inspired by https://www.printables.com/model/740517-beamcase-sff-modular-itx-case Which is outstanding, yet I wanted to make my own.
The author marked this model as their own original creation.