FRP: fibre reinforced plastic the plastic is a polymer most usually made of vinyl or sometimes epoxy. fibres are then used to reinforce the properties of the plastic. Fibres are usually strips of fibreglass. F : fibre simple. strips of pretty much grass like material. low density, low strength. PU: polyurethane plastic. simple. high density solid. carbon fibre: cluster of carbon strips that have been hardened through baking. low density. extremely high strength.