A small bat signal build that's really easy for survival. I put terracotta, concrete, blocks of coal and obsidian in for texturing, but you can do the build with just yellow and black wool.

I also put a lighthouse in the world with the signal on top with a small projection kind of thing, but I'm sure I could make an actual one if people actually use the map.

You can, of course, download the schematic and do whatever you want with it on the world.