#Uncraftable Items This list generated against spigot 1.9.4 Material lists, which also cantains a lot of internal items / blocks which may be obtainable by crafting, like the BED_BLOCK which can be placed using a BED_ITEM...
EDIT: I quickly looked over the list and removed the most obvious ones, just comment if you find any more of these blocks 😄
- AIR
- GRASS
- COBBLESTONE
- SAPLING
- BEDROCK
- SAND
- GRAVEL
- GOLD_ORE
- IRON_ORE
- COAL_ORE
- LOG
- LEAVES
- LAPIS_ORE
- WEB
- LONG_GRASS
- DEAD_BUSH
- YELLOW_FLOWER
- RED_ROSE
- BROWN_MUSHROOM
- RED_MUSHROOM
- OBSIDIAN
- MOB_SPAWNER
- REDSTONE_WIRE
- DIAMOND_ORE
- CROPS
- SOIL
- REDSTONE_ORE
- ICE
- CACTUS
- SUGAR_CANE_BLOCK
- PUMPKIN
- NETHERRACK
- SOUL_SAND
- PORTAL
- CAKE_BLOCK
- MONSTER_EGGS
- HUGE_MUSHROOM_1
- HUGE_MUSHROOM_2
- PUMPKIN_STEM
- MELON_STEM
- VINE
- MYCEL
- WATER_LILY
- NETHER_WARTS
- ENDER_PORTAL
- ENDER_STONE
- DRAGON_EGG
- WOOD_DOUBLE_STEP
- COCOA
- EMERALD_ORE
- TRIPWIRE
- COMMAND
- CARROT
- POTATO
- SKULL
- QUARTZ_ORE
- LEAVES_2
- LOG_2
- BARRIER
- DOUBLE_PLANT
- CHORUS_PLANT
- CHORUS_FLOWER
- PURPUR_DOUBLE_SLAB
- BEETROOT_BLOCK
- END_GATEWAY
- FROSTED_ICE
- STRUCTURE_BLOCK
- APPLE
- STRING
- FEATHER
- SULPHUR
- SEEDS
- CHAINMAIL_HELMET
- CHAINMAIL_CHESTPLATE
- CHAINMAIL_LEGGINGS
- CHAINMAIL_BOOTS
- FLINT
- PORK
- WATER_BUCKET
- LAVA_BUCKET
- SADDLE
- SNOW_BALL
- MILK_BUCKET
- CLAY_BALL
- SUGAR_CANE
- EGG
- GLOWSTONE_DUST
- RAW_FISH
- BONE
- MAP
- RAW_BEEF
- RAW_CHICKEN
- ROTTEN_FLESH
- ENDER_PEARL
- BLAZE_ROD
- GHAST_TEAR
- NETHER_STALK
- POTION
- SPIDER_EYE
- MONSTER_EGG
- EXP_BOTTLE
- CARROT_ITEM
- POTATO_ITEM
- POISONOUS_POTATO
- SKULL_ITEM
- NETHER_STAR
- ENCHANTED_BOOK
- PRISMARINE_SHARD
- PRISMARINE_CRYSTALS
- RABBIT
- RABBIT_FOOT
- RABBIT_HIDE
- IRON_BARDING
- GOLD_BARDING
- DIAMOND_BARDING
- NAME_TAG
- COMMAND_MINECART
- MUTTON
- CHORUS_FRUIT
- BEETROOT
- BEETROOT_SEEDS
- DRAGONS_BREATH
- SPLASH_POTION
- ELYTRA
- GOLD_RECORD
- GREEN_RECORD
- RECORD_3
- RECORD_4
- RECORD_5
- RECORD_6
- RECORD_7
- RECORD_8
- RECORD_9
- RECORD_10
- RECORD_11
- RECORD_12
Technically the chainmail armor WAS craftable, but you crafted it with fire which is unobtainable as item, even with commands.
Not sure if it is still the case.