Stats:
-41 tiles (10x4 floors plus explorable) tall from sealevel.
-Y coordinate while standing on roof is 106.6 (under clouds). On the highest point (the top of a tree on the P) is 113.6 (above clouds).
-T has a waterfall to bedrock.
-P has a large stairwell in the trunk to bedrock.
-U has a small stairwell on each side to bedrock.
-U has approximately 150 obsidian blocks.
-P has well over a 1000 wood.
-P has a house (house is visible, farm is above it) and farm in it.
-Animals spawn on the roof of the P.
-There is an underwater tunnel with glass roof connecting the three letters.
-There is another underwater tunnel connecting said tunnels to the spawn area with minecarts running in it.
-Joe's pic was taken from the corner of the T.
-The big TPU is 8:1 of the small one.
-TPU is etched into the glass as if it were casting a shadow. The ice clone is a 1:1 clone (except places where the ice was destroyed by creepers and the like).
-It's location in the world was completely random but it just so happens that a few tiles in front of the P is 0,60,0--almost dead center of the world.
-The base of all three letters extends to stone in cobblestone. Those cofferdams were used to eliminate the water from within the towers.
Cartographer render of the world. The ice-eteched TPU is clearly visible:
The TPU almost didn't happen. I was about to abandon my glass shack for another home somewhere else and that idea dawned on me. The final appearance of T and U was always known (glass, water, obsidian, and lava). The P was dirt before it became wood.