Door and board carriers need to be fairly strong, for carrying heavy materials, but should be light, so they don’t add much to the weight. Carriers can be made from various materials. What they are made of is likely to affect what they can be used to carry, how expensive they are, and how durable they will be.
Plastic
Some base door and board carriers are made entirely from plastic. Plastics are generally weak, compared to metal. Plastic can wear and split over time, especially plastics which are not heavy-duty. If exposed to cold weather, plastic can become very brittle. However, it is lightweight, inexpensive and easy to maintain.
Metal
Carriers used for lifting heavier materials need to be much stronger than plastic carriers. Steel or aluminium alloys are used to make some base carriers, and all clamping carriers.
Aluminium
Aluminium is often used to make board carriers because it is very light but still strong. It should be much stronger than plastic and high-quality aluminium carriers will be nearly as strong as steel, but can be expensive.
Steel
Steel carriers will be heavier than aluminium ones, so will add to the weight of the sheet material. Steel should be stronger than aluminum and often cheaper, but it can rust.
Which material?
Plastic carriers are generally the cheapest, but weakest. Steel will be more expensive than plastic, but it will be the strongest material. Aluminum is likely to be the most expensive, but will be lightweight, strong and easy to maintain.