The plastic is manufactured on the basis of at least four starting components (A, B, C, F) of which at least a first primary component (A) and a second primary component (B) can react with one another. A chemical reaction of the two primary components (A, B) is accelerated in such case by addition of at least one secondary component (C) serving as catalyst. Additionally, in the method of the invention, a tertiary component (F) serves as a filler, especially a color-giving filler. In the method of the invention, initially a first multicomponent system (BF; CF; BCF), especially also a storable system, serving as an intermediate component, is formed, which contains, at least in part, both the secondary component (C) as well as also the tertiary component (F). Additionally, on the basis of the first multicomponent system (BF; CF; BCF) a flowable, especially liquid, second multicomponent system (ABCF) is formed, which contains the four starting components (A, B, C, F) in concentrations enabling the chemical reaction of the primary components (A, B). The plastic is finally formed by means of the second multicomponent system in that the therein contained primary component (A) and the therein contained second primary component (B) are allowed to react, at least partially, with one another. By applying the second multicomponent system (ABCF) onto an inner wall of a support tube, especially a metal support tube, serving as a component of an in-line measuring device, a liner internally coating the support tube can be formed from this plastic in simple manner.