The issue is patents. Open Source derives it’s power from copyright law – they use the property right of “copyright” and then pool it by using the GPL and other such licenses which rest on copyright.
Patent is a huge pain in the ass. You could do an open source patent pool, but that’s a very expensive and hard to manage undertaking.
So… one option is to work in the domain of no property rights – public domain – which is where a manufacturing technology goes if it is disclosed without patents, or is patented but the patent has expired.
But then what if you publish your design, then somebody makes a small tweak which kind of perfects your design, and then patents their tweak – without a patent on the original item, you can’t require them to release their changes for general use, because there’s no property right that you hold which applies to their work.
A problem, for sure, in terms of doing Open Manufacturing in the same vein as Open Source.