You've probably heard the saying "one man's trash is another man's treasure." This holds true for most scrap farming. Especially when it comes to designing pens, coops, and other special projects around the yard or farm with pallets.
If you want to build any structure on a budget the sky's the limit when it comes to designing with pallets and even their spare parts. A good starting place to look for affordable if not free material is the back of a store in your local area. Most businesses will simply give away their pallets that are not marked with paint for return to the manufacturer.

It is always recommended to ask a manager or owner before taking items from any property. It is possible to find some pretty awesome treasures around town. Discarded pallets and other wooden items have been used to create fencing, gates, roosts, storage shelves for large items even a small shed for storage. Just remember as a rule if the pallet is painted on the ends like the one above you should leave it because it is marked for return and the store might lose money if you take those.
Pallets come in many different sizes and varieties. You can build a sizable enclosure for a variety of animals with minimal supplies. By connecting the pallets using scrap wood along the top and sides using nails or screws you create a durable almost impenetrable wall to keep your animals in. Pallets dramatically decrease construction time. I have on three different occasions designed and put up a chicken coup primarily designed out of pallets in less than one full day. They are like magic!
Enclosures such as chicken coops are easily assembled using pallets as walls. Garden netting can be purchased from your local hardware store or big box store and used as a roof for your coop. T-posts or tall pieces of wood can be used to hold up the netting and ensure average sized humans are able to walk around inside the enclosure and perform chores. Using zip-ties you can connect the netting in those tricky places and patch up any holes.
The netting pictured above is available from Lowes for $19.99 and it was a roll of 100ft x 7ft. That is more than enough to cover a very large enclosure or several different coops.
The main reason to cover your enclosure or coop is to protect the animals from predators. Owls, hawks, opossums, and raccoons that can enter the enclosure or coop if you do not secure it from secure it properly. The extra netting can be wrapped around the coop to prevent entry through any breaks in the walls.
Let me know if you have any questions or if you have any success stories using pallets in your scrap farming experience. I stand by the versatility of pallets and firmly believe you should keep looking if you are unable to acquire some for free in your area.