Code:
on place of light gray concrete powder:
make console execute command "/summon endermite %event-location%"
make console execute command "/execute @e[type=endermite] ~ ~ ~ setblock ~ ~ ~ structure_block 0 replace {mode:"LOAD",posX:0,posY:0,posZ:0,sizeX:3 ,sizeY:5 sizeZ:3 name:"stonegen",powered:0b}"
make console execute command "/execute @e[type=endermite] ~ ~ ~ setblock ~ ~1 ~ redstone_block"
make console execute command "/kill @e[type=endermite]"