Cove mitres can be made of either metal or plastic.
Steel
Steel is the metal used to make cove mitres that are often referred to as being professional, or for trade use. This is because steel is a relatively cheap metal that is easy to form into the desired shape and provides the strength and wear resistance required of a long-lasting cove mitre.
Steel cove mitres do not wear from having the saw blade run along their sides, so will outlast cove mitres made of plastic. This is an important attribute to consider if you are going to be using one a lot.
Metal cove mitres cost more than plastic ones, often being around double the price. However, as they last much longer they can be more cost effective in the long term if they are frequently used.
Plastic
Plastic cove mitres are often referred to as being DIY cove mitres. Plastic versions wear as the saw blade runs down their sides, which means they are only suitable for limited use before they wear and require replacing. This makes them unsuitable for a professional tradesperson who uses them a lot.
Plastic cove mitres are approximately half the price of a metal one, so if you are only fitting coving in one room they may be a cheaper option.
