How To Make A Minecraft Dispenser / Automated Bow / Dispenser Trap
One of the more amusing toys included in the Minecraft 1.2 Beta update was the Dispenser. Created with seven cobblestone, one bow and one piece of redstone, the dispenser has the ability to store all manner of useful objects and hurl them out of itself at high speed. It is particularly useful in a defensive function if it is stocked with arrows.
How To Craft A Minecraft Dispenser
When the dispenser is clicked on, you will see that it has up to nine slots which can store items to be fired or 'dispensed'. This provides quite a bit of capacity.
How To Power A Minecraft Dispenser
But all this space is fairly useless if you don't know how to hook up a dispenser. In order to fire your Minecraft dispenser, you will need to make a trail of redstone dust to it and use a switch or pressure plate or similar device to activate dispenser. When the redstone glows, the dispenser will fire one arrow (or block, or flower, whatever you put in it) you can fire rapidly by toggling a switch back and forth.
How To Make A Dispenser Mob Trap
As with pretty much anything made using redstone, the dispenser has a definite potential for traps. Because you can use stone pressure plates to power the dispenser, it is a very simple matter to line the plate up with the front of the dispenser, thus creating an 'Indiana Jones' style trap. This is an incredibly simple trap to make and I can't tell you how funny it is to be going about your business elsewhere on your Minecraft property and hearing the dispenser being set off by half-witted mobs who apparently don't mind being riddled with arrows.
The noise that the trap makes is also a potential warning system, letting you know that something (or someone, if this is implemented in SMP) is getting a little too close for comfort.
PRO TIP: A dispenser will 'dispense' through solid blocks. Dispensers can be hidden in walls. Use this information wisely.
The Double Dispenser Minecraft Trap
My experiments with the dispenser arrow trap have lead me to the conclusion that two dispensers, stacked one atop the other and filled with arrows can be triggered to fire simultaneously if the lower of the two is hooked up to a redstone switch of some kind (it can be a traditional switch, or a pressure plate, I personally think a pressure plate is the only way to go for a trap, but if you plan to 'man the cannon' yourself, then a switch will give you the control you desire and won't depend on the mob or enemy player accidentally wandering all over pressure plates.