When choosing a block and tackle, think about your purpose for using the equipment, the cost, and the ease of use. Block and tackles are pulley systems used to exchange force for distance, so you need a set-up that is the correct size for your purpose. You can purchase a block and tackle at a store or make one yourself with ropes and pulleys, depending on your budget and whether you have a tendency towards do-it-yourself projects.
A block and tackle allows you to hoist items that you normally would have difficulty lifting due to their heavy weight. The basic block and tackle system consists of a rope and a pulley attached to a high surface. This simple system splits the weight of the object you are lifting by half. Once more pulleys are added, the weight decreases even more, but the distance that you have to pull the object increases as well. You need to consider these factors when choosing the right block and tackle for your situation.
If you are lifting extremely heavy objects, you can look at systems that involve more pulleys. For lighter items, a more simple system would likely work. You have to decide whether you would prefer to lift more weight a shorter distance, or less weight a longer distance. This depends on your personal strength, the willingness you have to lift a heavy object, and whether you have help with the block and tackle rig.
The cost of a block and tackle system is also an important factor when making a choice. You can purchase block and tackle rigs at many home and hardware stores. Ask for demonstrations of the different systems before purchasing one so that you can compare the ease of use versus the cost. If the system is overly complicated, you might have a more difficult time using it. Once you have decided upon your budget for the item, you can narrow down the available systems to choose one that fits in your price range.
It is also possible to make your own block and tackle rig using ropes and pulleys that you purchase from a home or hardware store. This is more complicated, so you should only choose this option if you are fairly handy with building materials and have the proper tools to assemble the system. Building your own system can save you money but can also take valuable time away from other projects.