Minecraft wiki entry for Time-saving_tips, associated text: Made a mistake when building something? Do you now have to destroy and replace a large number of blocks? This may be a case where pistons can help. First, put gaps in key places so that no single run of blocks is more than twelve meters long. Then put temporary 'filler' blocks in any remaining gaps. Then place one or more pistons, and use it or them to nudge each section of blocks back into position. This tip is most useful when the initial block placement is complex, such as when drawing pixel art using wool, or for buildings with advanced decorative embellishments, or when using materials that cannot be removed without the silk touch enchantment, such as ice, glass or smooth stone. With care, you can even use this trick to move small buildings.