PBP Lightsabers

Combine an amethyst shard with red, green, blue, white, or purple dye in a crafting table to get a colored amethyst shard.

Combine two colored amethyst shards with a netherite ingot in a smithing table to get a colored netherite ingot.

With the netherite ingot, right click a block of amethyst to transform it into a colored amethyst block.

Right click the colored amethyst block four more times to grow the kyber crystal.

Once the kyber crystal is fully grown, you can mine it with a diamond pickaxe (or any diamond-level or higher pickaxe) to get the kyber crystal.

Stack two iron ingots on top of each other in the crafting table to make lightsaber hilts.

Put the lightsaber hilt in the bottom left corner of the crafting table, the kyber crystal in the middle, and a colored amethyst shard (matching the color of the kyber crystal) in the top right corner. And you have just made your very own lightsaber!