If you want to make a glow sign in Minecraft, you will first need to make a normal sign. You can make a sign with six wood planks and one stick as shown by the pattern below.
Once you built a sign, you will then need to place it anywhere you want. After this, you can then turn it into a glow sign by using both dye and a glow inc sac. To get the glow ink sac, you will need to kill a glow squid, which can be tricky to do since they only spawn deep underwater.
We recommend making respiration potions or enchanting a helmet with respiration one or two to make getting to the squids easier. Also, make sure to bring a weapon enchanted with looting three along for the ride so you can get an increased glow ink sac drop rate.
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When you get the ink sac, place it on your Hotbar, and then right-click the sign after inputting text. Doing so will then light up the text on the sign for you, but that's not the end of it. You can also change the color of the glowing text by righting it with a dye equipped to your hot bar.