Find a frozen ocean biome
Locate packed ice blocks
Use a Silk Touch pickaxe to mine packed ice
Craft blue ice with 9 packed ice blocks in a crafting table
Build a large packed ice farm if you need more
Use a beacon with Haste for faster mining
Mine in Creative mode for instant blue ice
Trade with other players if available
Use commands if cheats are enabled
Duplicate with glitches only if allowed on your server