https://en.wikipedia.org/wiki/Blinkenlights

The “blinkenlights” sign has been around in numerous versions since at least the 1960s in the earliest days of computing, using a mix of really bad (but funny) pseudo-German text to warn against touching the equipment. I made my own version with the “Make My Sign” feature of MakerWorld to put on my new X1C/AMS combo. Because of the intricacy of the blackletter text it should be printed as large as possible. I found that it turned out better with the “flat sign” function turned on than with using embossed/risen text.