Gem Bomb (Courtesy of Launisch)

summon FallingSand ~ ~1 ~ {Block:stone,Time:1,Passengers:[{id:FallingSand,Block:redstone_block,Time:1,Passengers:[{id:FallingSand,Block:activator_rail,Time:1,Passengers:[{id:MinecartCommandBlock,Command:gamerule commandBlockOutput false},{id:MinecartCommandBlock,Command:"fill ~2 ~-3 ~-1 ~5 ~-1 ~1 stained_hardened_clay 5 hollow"},{id:MinecartCommandBlock,Command:"fill ~2 ~-2 ~-1 ~5 ~-2 ~1 stained_glass 4 replace stained_hardened_clay"},{id:MinecartCommandBlock,Command:" /give @a emerald 1 0 {display:{Name:\"Gem Bomb\"}}"},{id:MinecartCommandBlock,Command:" /scoreboard objectives add GemBomb dummy"},{id:MinecartCommandBlock,Command:setblock ~1 ~-3 ~ wall_sign 4 replace {Text1:"{\\\"text\\\":\\\"Gem Bomb\\\",\\\"color\\\":\\\"dark_green\\\",\\\"bold\\\":true}",Text2:"{\\\"text\\\":\\\"by Graystriped\\\",\\\"color\\\":\\\"dark_green\\\",\\\"bold\\\":true}",Text3:"{\\\"text\\\":\\\"Courtesy of \\\",\\\"color\\\":\\\"dark_green\\\",\\\"bold\\\":true}",Text4:"{\\\"text\\\":\\\"Launisch\\\",\\\"color\\\":\\\"dark_green\\\",\\\"bold\\\":true}"}},{id:MinecartCommandBlock,Command:setblock ~1 ~-2 ~ wall_sign 4 replace {Text1:"{\\\"text\\\":\\\"[Destroy]\\\",\\\"color\\\":\\\"dark_red\\\",\\\"bold\\\":true,\\\"underlined\\\":true}",Text4:"{\\\"text\\\":\\\"\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"fill ~ ~-1 ~-1 ~4 ~1 ~1 air\\\"}}"}},{id:MinecartCommandBlock,Command:setblock ~4 ~-2 ~ chain_command_block 5 replace {auto:1,Command:"/execute @e[score_GemBomb_min=1] ~ ~ ~ /summon Item {type=emerald}"}},{id:MinecartCommandBlock,Command:setblock ~3 ~-2 ~ repeating_command_block 5 replace {auto:1,Command:"/scoreboard players set @e[type=Item] GemBomb 1 {Item:{id:\\\"minecraft:emerald\\\",tag:{display:{Name:\\\"Gem Bomb\\\"}}}}"}},{id:MinecartCommandBlock,Command:setblock ~ ~ ~1 command_block 0 replace {Command:fill ~ ~-3 ~-1 ~ ~ ~ air}},{id:MinecartCommandBlock,Command:setblock ~ ~-1 ~1 redstone_block},{id:MinecartCommandBlock,Command:kill @e[type=MinecartCommandBlock,r=1]}]}]}]}