I recently read a post with someone showing how you could use the paint tool on crystal blocks and it would render them transparent and I think I may have found a practical use for it. (...that doesn't consist of confusing players in multi-player by encasing them in it) After several attempts at constructing some sort of oceanic base (Sealab 2021 anyone?) I realized you couldn't build a proper one against the planet's backdrop and they all seemed to looked as if they were in an underwater cave. Unless... You use the crystal blocks for the background blocks like so... ...choose any color with your paint-tool and paint all of the crystal blocks, leaving a transparent barrier for your water. Add the dihydrogen monoxide and voila! You can now have a scenic view at 200 fathoms. If you have any other clever uses for this, feel free to throw them at me. I'll post images of some of the different designs I've worked on in the near future. Feel free to post your ideas and screenshots - inspiration often lies with others. Chucklefish - Where are my Ocean planets?
I could see this being used in some giant fish-tank, if they finally a use. Or, maybe a fountain? You can enclose the water with invisible blocks to make it look like the water is floating.
Well, you can use a mod like CreativeMode, which you can only use by crafting something, so you can have just one player you use the Mod on, and the others would be legit. I do that myself.
Without rain, or a crazy amount of work to channel the water from somewhere else, no. The Liquid Extractor mod works EXCELLENTLY for this purpose. It lets you take blocks like ice, slush, snow, etc and melt it into water capsules that you can throw in the spot where you want your lake. It'll let you create capsules for other liquids too (lava, poison, blood, etc).