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Dave lists the 5 unwritten rules of Open Source Hardware (OSHW), that have essentially been around since the very early electronics magazine project days.
These are over an above the legal obligations under whatever license is used.
#1 Don’t clone. Innovate.
#2 If you sell it, you support it.
#3 Give the original author a cut
#4 Respect the wishes of the original author
#5 Don’t use the original authors name or project name