This little "tutorial" if you will, is for those who are new to the minecraft tool, and don't know any better. First of all, if you do any of these, it WILL destroy your save. Do NOT add items which are currently unavailable in this version of minecraft (due to change to 1.7 soon) this includes, Pistons, Melons, Ender Pearls, (there are many more, will create a list after this tut) Do NOT change the 100 (boots) 101 (leggings) 102 (chest-plate) 103 (helmet) to any other item, these ID codes are for armor only.. changing them to anything will destroy your save, (it is possible to change the helmet to a block, but i recommend against it) Do NOT stack un-stackable items, these are items such as pickaxes, armor, crafting tables, etc. Do NOT think you can do any of the above, it WILL destroy your save no matter who you are. Remember to rehash and resign. List of what NOT to add. Spoiler Air blaze powder blaze rod brick slab brick stairs cactus green chainmail boots chainmail leggings chainmail chestplate chainmail helmet clock cobblestone (silverfish) cobblestone slab coco beans cooked chicken cracked stone brick dead shrub dead shrub 2 any double slabs. ender pearl fence gate fremented spider egg fire ghast tear glass bottle glass pane gold nugget lily pad live shrub locked chest magma cream melon melon block melon seeds melon stem mossy stone brick mycelium nether brick nether brick stairs nether brick fence nether warts nether seeds potion pumpkin seeds pumpkin stem raw beef raw chicken raw fish redwood redwood leaves redwood sapling rotten flesh shears snow soil spider eye stationary lava stationary water stick stone (silverfish) suarcane (not sure what this is) sulphar tall grass vines water as said before after the update pistons should be addable. Un-Stackable items. Spoiler workbench water bucket water wall sign steak sign saddle all minecarts map all armours lava bucket music discs all shovels all pickaxes all hoes all swords all axes golden apple flint and steel fishing rod bucket bed there are more then likely more un-stackable items, be weary and tell me if i have missed some.