A method of imparting at least one functional characteristic to a portion of an engine, said method comprising: providing at least a portion of an engine comprising a surface; providing different particle feedstocks, with at least one of the particle feedstocks comprising particles that are different from another of the particle feedstocks; and depositing particles from each of the different particle feedstocks so as to form a high temperature resistant coating on at least part of the surface of the engine portion, with the high temperature resistant coating having a thickness and a surface area, wherein said depositing comprises a step of depositing the particles, each of the different particle feedstocks is used as a source of particle material during the step of said depositing, and at least one functional characteristic corresponds to using the different particle feedstocks during the step of said depositing, said method further comprising providing a particle deposition device and a plurality of powder feeders connected to a particle feedstock delivery port mounted on the particle deposition device, wherein each of the different particle feedstocks is delivered to the particle feedstock delivery port through a different one of the powder feeders, wherein the powder feeders are activated and deactivated in sequence to vary the particle feedstock delivered to the particle feedstock delivery port to form the high temperature resistant coating, wherein the particle deposition device is operated continuously whilst the powder feeders are being activated and deactivated such that the high temperature resistant coating is a continuous coating with no distinct interface discernable between adjoining layers of the coating, wherein the particle deposition device comprises a plasma particle spray gun, characterised in that: each of the plurality of powder feeders is connected to the same particle feedstock delivery port; and the different particle feedstocks have the same chemical composition but vary in the amounts of particles of different sizes making up the feedstock. providing at least a portion of an engine comprising a surface; providing different particle feedstocks, with at least one of the particle feedstocks comprising particles that are different from another of the particle feedstocks; and depositing particles from each of the different particle feedstocks so as to form a high temperature resistant coating on at least part of the surface of the engine portion, with the high temperature resistant coating having a thickness and a surface area, wherein said depositing comprises a step of depositing the particles, each of the different particle feedstocks is used as a source of particle material during the step of said depositing, and at least one functional characteristic corresponds to using the different particle feedstocks during the step of said depositing, said method further comprising providing a particle deposition device and a plurality of powder feeders connected to a particle feedstock delivery port mounted on the particle deposition device, wherein each of the different particle feedstocks is delivered to the particle feedstock delivery port through a different one of the powder feeders, wherein the powder feeders are activated and deactivated in sequence to vary the particle feedstock delivered to the particle feedstock delivery port to form the high temperature resistant coating, wherein the particle deposition device is operated continuously whilst the powder feeders are being activated and deactivated such that the high temperature resistant coating is a continuous coating with no distinct interface discernable between adjoining layers of the coating, wherein the particle deposition device comprises a plasma particle spray gun,