To fully power a beacon, you need diamond, gold, iron, and or emerald blocks to create a 9x9, 7x7, 5x5 and 3x3 hill of blocks. On top of these blocks you need to place a beacon, which can be created by using 3 obsidian, 5 glass and 1 nether star. Acquiring this amount of blocks can take a very long time.
Therefore, I've uploaded a world with a fully powered beacon to dropbox. Simply destroy the top bit of the beacon and place it again to unlock the achievement.
Download the Beacon+sponge world. https://www.dropbox.com/sh/v6ggssr1ag7uerp/AACU3QfRen68hOMno...
If you're unsure how to get these worlds to work in minecraft, this thread might help. Achievement worlds