Blue Robotics has making their original (non-locking) watertight enclosure designs fully open source and available for anyone to use or modify. Watertight enclosures are a fundamental component needed in all sorts of subsea applications and these now open-source enclosures are a great starting point for anyone interested in designing their own enclosures.
The designs are licensed under the Creative Commons CC BY 4.0 license, allowing you to copy, redistribute, transform, or build upon the design for commercial and non-commercial purposes, the only term being that you give attribution to Blue Robotics. Basically, do whatever you want and share credit if the files were valuable to you!
Files available here for 2″, 3″ and 4″ cast acrylic enclosures and flanges