3D Print in progress sign

I've been doing some public 3D printing events and I found myself needing a sign to show when the 3D printer was running and the lame paper sign wasn't cutting it. We need a 3D printed sign!

I searched thingy and found this thing https://www.thingiverse.com/thing:1761855 by ideawizard. It was close, but not quite what I was looking for.

So here's my take on a 3D print in progress sign!