So Esarai did science... and after a lot of spectacular crashes, peculiar sights and mineverse-shattering paradoxes, has produced the first working version of his personal plugin 'CannonSigns.'

Now, enough of the third person. While I'm implementing the permissions, I've given everyone the permissions to use this plugin until I can better regulate who uses what type of cannonsign. Consider this a general tutorial.

To make a cannon, place a line of iron blocks, and at one end, affix a sign with either [Cannon], [Scattergun] or [Mortar] in the 1st line. This is case sensitive, so do be sure to get it right. Now, you can either right click on it, or power it with redstone to fire. The flight time of each shell is preset, and the number of iron blocks you used determines the velocity. So, for further range, use more iron.

To make a turret, place an iron block with a sign affixed to it. The sign should have [Turret] on the first line, one of TNT, Flak or HMG on the second, and a 2 digit number on the third. Then, in the 3x3x3 cube around this iron block, add more iron blocks and a lapis block. Make sure the lapis is on the side opposite the sign, or else the shells will get stuck in the turret and it wil explode. Now that it's all set up, right-click on the sign with a blaze rod to arm the turret, right click in air to fire in the direction you are looking, and right click the sign again to stop firing.

Let there be boomy goodness.