Randomly Spawing Structures In One Command {Raw}

Signs:
/give @p spawn_egg 1 383 {display:{Name:"Spawn_Structure_Creator"}}
/summon ArmorStand ~ ~ ~ {CustomName:"Structure_Clone",Invisible:1,NoGravity:1}

Commands:
/execute @e[name=Spawn_Structure_Creator] ~ ~ ~ /setblock ~4 ~ ~4 stained_glass 3
/execute @e[name=Spawn_Structure_Creator] ~ ~ ~ /setblock ~4 ~ ~-4 stained_glass 3
/execute @e[name=Spawn_Structure_Creator] ~ ~ ~ /setblock ~-4 ~ ~4 stained_glass 3
/execute @e[name=Spawn_Structure_Creator] ~ ~ ~ /setblock ~-4 ~ ~-4 stained_glass 3
/execute @e[name=Spawn_Structure_Creator] ~ ~ ~ /setblock ~4 ~10 ~4 stained_glass 3
/execute @e[name=Spawn_Structure_Creator] ~ ~ ~ /setblock ~4 ~10 ~-4 stained_glass 3
/execute @e[name=Spawn_Structure_Creator] ~ ~ ~ /setblock ~-4 ~10 ~4 stained_glass 3
/execute @e[name=Spawn_Structure_Creator] ~ ~ ~ /setblock ~-4 ~10 ~-4 stained_glass 3
/kill @e[name=Spawn_Structure_Creator]
/spreadplayers ~ ~ 50 500 false @e[name=Structure_Clone]
/execute @e[name=Structure_Clone] ~ ~ ~ /clone -993 56 861 -998 60 866 ~ ~ ~ masked
/scoreboard objectives add SCTime dummy
/scoreboard players add @e[name=Structure_Clone] SCTime 1
/kill @e[score_SCTime_min=1]