Parody and transformative work is part of the copyright law to which this adhears to. Your lawnmower analogy is illogical as what's actually happening is that 'someone' is 3d printing their own lawnmower instead of taking yours.
Not to derail this thread too far from topic but you misunderstood me.
The first paragraph of my comment concerned the pornographic images taken from the net. Those are not free to use, and copying them into your work (the game) is not as a general rule allowed and is not under any law I know about covered under any fair use clause.
The second paragraph concerned exactly what you are talking about, I pointed out the
potential fair use exceptions. Those are not universal across every jurisdiction and
pornographic works in particular are not clearly covered. Perhaps you are talking about USA law? In that case, I'm not an american lawyer, and never stated that porn parodies is or is not covered under US law.
My analogy wasn't illogical, but of course any analogy breaks down if you move it to a wholly different context.
Now...back to what this forum is really about, big badonkadonks.