Thank you for your suggestion, GEE 🙂 There will be a in-depth specification of the STEMFIE dimensional standard, so that everyone can develop compatible parts. Please stay tuned via https://newsletter.stemfie.org. I also plan to release the STEP files in the future for the very purpose of what you mentioned: community contributions.
I wish the STEMFIE project to mature a bit and will be releasing a few more projects shortly. That will probably mature the design, making it ready for STEP file release.
Cheers. 🙂
Paulo