This is my modified version of a TNT cannon from one of my favorite minecrafters who shall remain nameless! For this, all you need is 8 blocks of TNT, 3 or 1 or 2 or however many you want of any solid block that is not a slab (i used stone bricks, my personal favorite), a slab of any kind (again, I used stone brick), enough water, a button, 16 redstone dust, and 6 glass panes. Watch the video on instructions on how to build. I do not take full credit for this, I take part credit, as it is a MODIFIED VERSION of a TNT I saw. Please fav and give diamonds! MWA HA HA!