For example if I create a python script that generates imagery in one form or another and I want to both be able to share that code for others to improve, modify or whatnot and also to be able to sell prints of the outputs, what license would one choose for the script?
Would need to know more, but what the software produces is not covered by the license, at least not if you use regular known FLOSS licenses. Say you GPL your software source code, nothing prevents you to sell what is generated with it (and nothing prevents others to do so as well). But maybe you mean something else?
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