As I found recently you can fill a cauldron that is underwater with lava.. I understand that this probably isn't meant to happen but what if it was?
So you place a cauldron underwater, fill it with lava and a block of obsidian pops out!
You can do this 5 times before the cauldron breaks. This avoids the elimination of mining obsidian as the cost of the replacing cauldron would outweigh mining.
it would be cool to see the cauldron explode and leave 1 block of obsidian or even the iron ore block when it's full of lava and underwater, and get filled with water if it's filled with snow underwater instead
That would be awesome!
While i don't like obsidian as a building block i think many people would be happy about this method to farm obsidian.
I don't see any balancing issues nowdays.
-Illigal Structures (mod)