I want to be able to make all of one type of a block in a world look like another. I have nether portals in my spawn... ... but the obsidian doesn't fit the spawn's theme of stone slabs. How make all obsidian in the spawn world look like double stone slabs (ID=43:6)? Also, i cant use worldedit, etc. to change the obsidian because i have a plugin that makes the portals teleport to a specific place. Changing the obsidian will make the plugin not work. Thanks!