You can get wool by shearing sheep, killing sheep, or crafting it out of string. Shearing sheep is often advantageous as it means that they can regrow their wool by eating grass. They will eat grass as soon as it grows, meaning observers can be used to detect this and activate dispensers, which can shear sheep if their hitbox is in the block in front of the dispenser.
The wool will fall off and will usually go into a hopper for collection.
Automatic sheep shearing design
There are many designs that can be stacked to make large wool farms. The sheep can also be dyed to produce different wool colors.
How to build an automatic wool farm
- Place down a dispenser facing horizontally.
- Lay down grass blocks 1 block lower and one block in front of the dispenser.
- Build a pen out of glass (preferably the color of the sheep).
- Lure a sheep inside or create a piston contraption to move the sheep into the pen.
- Put an observer underneath the dispenser facing at the grass block to power the dispenser,
- Then put a piece of Redstone Dust on top of the block behind the Observer (which is in behind the dispenser) to power the Dispenser.
- Put a shear into the dispenser.
- Place minecarts with hoppers underneath the grass to collect the items.
- Make a room full of chests that the minecarts bring the wool into.
An Infinite Automatic Wool Farm
This machine provides you with infinite wool, and does not take many resources at all. After building the machine, all you have to do is replace the shears if they break, which does not happen very often.
- Build a 1 by 2 dirt platform and surround it with a wall that is as high as you want made of glass blocks.
- Under the dirt blocks place two hoppers connected to a double chest.
- Build a staircase to the top of the wall and lead a sheep of any color into the container. After the sheep is trapped, put a glass roof onto the container.
- Knock out one of the glass blocks that are 1 block above the dirt platform and place a dispenser in its place, making sure the dispenser faces the sheep. Place a pair of shears in the dispenser.
- Connect the dispenser to a redstone clock so it shears the sheep every few seconds.