Toggle gravity in minecraft vanilla | no mods-one cm edition

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:scoreboard objectives add i dummy},{id:MinecartCommandBlock,Command:setblock ~1 ~-3 ~ repeating_command_block 1 replace {auto:1,Command:"/scoreboard players add @e[type=!Player] i 1"}},{id:MinecartCommandBlock,Command:setblock ~1 ~-2 ~ chain_command_block 1 replace {auto:1,Command:"/entitydata @e[type=!Player,score_i_min=1,score_i=1] {NoGravity:1b}"}},{id:MinecartCommandBlock,Command:setblock ~1 ~-1 ~ chain_command_block 1 replace {auto:1,Command:"/entitydata @e[type=FallingSand] {Time:1b}"}},{id:MinecartCommandBlock,Command:setblock ~2 ~-1 ~ wall_sign 5 replace {Text1:"{\\\"text\\\":\\\"My channel\\\",\\\"color\\\":\\\"dark_blue\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"/tellraw @a [\\\\\\\"\\\\\\\",{\\\\\\\"text\\\\\\\":\\\\\\\"Remember to take a look of my channel: \\\\\\\",\\\\\\\"color\\\\\\\":\\\\\\\"gold\\\\\\\"},{\\\\\\\"text\\\\\\\":\\\\\\\"My channel\\\\\\\",\\\\\\\"color\\\\\\\":\\\\\\\"dark_aqua\\\\\\\",\\\\\\\"clickEvent\\\\\\\":{\\\\\\\"action\\\\\\\":\\\\\\\"open_url\\\\\\\",\\\\\\\"value\\\\\\\":\\\\\\\"https://www.youtube.com/channel/UC3_Gm-pfskCh2bnzcekR0ow\\\\\\\"}}]\\\"}}",Text2:"{\\\"text\\\":\\\"\\\",\\\"color\\\":\\\"aqua\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"/execute @a ~ ~ ~ playsound minecraft:entity.experience_orb.pickup voice @a ~ ~ ~ 12 1 1\\\"}}",Text3:"{\\\"text\\\":\\\"\\\",\\\"color\\\":\\\"dark_blue\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"2\\\"}}",Text4:"{\\\"text\\\":\\\"\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"3\\\"}}"}},{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]}]}]}]}