The first two photos are the iron farm that i made. It works by having the villagers in the boxing on the side spawn in iron golems. When iron golems spawn they flow with the water to the hole in the middle and when the fall they drop in lava and die. When they die they drop iron and then the iron flows with the water at the bottom to a hopper that transfers the iron to a chest to keep it in storage. I had some problems getting the right dimensions of the main platform so that the water would flow perfectly to the center without actually falling in the hole.
The last two photos are the TNT cannon that i helped Will create in his castle. It works by having an electric charge sent to the main TNT lighting it and then a delayed charge is sent to the projectile TNT so that it light after the main TNT when the main TNT explodes it doesn't damage anything because it is placed in water but it launches the lit projectile TNT towards the battlefield and then explodes when it hits the ground.
The last two photos are the TNT cannon that i helped Will create in his castle. It works by having an electric charge sent to the main TNT lighting it and then a delayed charge is sent to the projectile TNT so that it light after the main TNT when the main TNT explodes it doesn't damage anything because it is placed in water but it launches the lit projectile TNT towards the battlefield and then explodes when it hits the ground.