Copy and paste this command into a command block and then activate it to get exploding snowballs into your world.
Place the machine in the spawn chunk to make the machine work wherever you are.

Command to get a command block: /give @p command_block

This command is tested in 1.11 - 1.11.2 so if it don´t work use it in one of these versions.


The exploding snowballs command:

summon falling_block ~ ~1 ~ {Block:stone,Time:1,Passengers:[{id:falling_block,Block:redstone_block,Time:1,Passengers:{id:falling_block,Block:activator_rail,Time:1,Passengers:{id:commandblock_minecart,Command:gamerule commandBlockOutput false},{id:commandblock_minecart,Command:fill ~2 ~-3 ~-1 ~4 ~-1 ~1 snow 0 hollow},{id:commandblock_minecart,Command:fill ~2 ~-2 ~-1 ~4 ~-2 ~1 stained_glass 0 0 snow},{id:commandblock_minecart,Command:setblock ~1 ~-4 ~ wall_sign 4 0 {Text1:"{\\\"text\\\":\\\"\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"/give @p snowball\\\"}}",Text2:"{\\\"text\\\":\\\"get a snowball\\\"}",Text3:"{\\\"text\\\":\\\"\\\"}",Text4:"{\\\"text\\\":\\\"\\\"}"}},{id:commandblock_minecart,Command:setblock ~1 ~-3 ~ wall_sign 4 0 {Text1:"{\\\"text\\\":\\\"\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"scoreboard players add @etype=armor_stand,name=TogAct,c=1] zK1k3F_A 1\\\"}}",Text2:"{\\\"text\\\":\\\"Activate/deactivate\\\",\\\"color\\\":\\\"yellow\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"execute @e[score_zK1k3F_A_min=1,score_zK1k3F_A=1] ~ ~ ~ blockdata ~ ~ ~ {auto:0}\\\"}}",Text3:"{\\\"text\\\":\\\"the machine\\\",\\\"color\\\":\\\"yellow\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"execute @e[score_zK1k3F_A_min=2] ~ ~ ~ blockdata ~ ~ ~ {auto:1}\\\"}}",Text4:"{\\\"text\\\":\\\"\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"scoreboard players reset @e[score_zK1k3F_A_min=2] zK1k3F_A\\\"}}"}},{id:commandblock_minecart,Command:setblock ~1 ~-2 ~ wall_sign 4 0 {Text1:"{\\\"text\\\":\\\"\\\"}",Text2:"{\\\"text\\\":\\\"Destroy machine\\\",\\\"color\\\":\\\"red\\\"}",Text3:"{\\\"text\\\":\\\"\\\"}",Text4:"{\\\"text\\\":\\\"\\\"}"}},{id:commandblock_minecart,Command:setblock ~1 ~-1 ~ wall_sign 4 0 {Text1:"{\\\"text\\\":\\\"Exploding snowballs\\\",\\\"color\\\":\\\"white\\\"}",Text2:"{\\\"text\\\":\\\"command by:\\\",\\\"color\\\":\\\"green\\\"}",Text3:"{\\\"text\\\":\\\"xxhd23\\\",\\\"color\\\":\\\"gold\\\"}",Text4:"{\\\"text\\\":\\\"\\\"}"}},{id:commandblock_minecart,Command:summon armor_stand ~3 ~-2 ~ {CustomName:TogAct,Marker:1,NoGravity:1,Invisible:1}},{id:commandblock_minecart,Command:scoreboard objectives add zK1k3F_A dummy},{id:commandblock_minecart,Command:fill ~3 ~-2 ~ ~3 ~-2 ~ chain_command_block 5},{id:commandblock_minecart,Command:setblock ~3 ~-2 ~ repeating_command_block 5},{id:commandblock_minecart,Command:blockdata ~3 ~-2 ~ {auto:1,Command:/execute @p ~ ~ ~ execute @e[type=Snowball,c=1] ~ ~ ~ summon Fireball ~ ~ ~ {direction:[0.0,0.0,0.0],ExplosionPower:3}}},{id:commandblock_minecart,Command:setblock ~ ~ ~1 command_block 0 0 {Command:fill ~ ~-3 ~-1 ~ ~ ~ air}},{id:commandblock_minecart,Command:setblock ~ ~-1 ~1 redstone_block},{id:commandblock_minecart,Command:kill @e[type=commandblock_minecart,r=1]}]}]}]}