A process for manufacturing an object, the process comprising steps: a) selecting a feedstock material comprising one or more polymeric material selected from i) a polymeric material (A) having a repeat unit of formula I and a repeat unit of formula II wherein Ph represents a phenylene moiety; and/or ii) a polymeric material (B) having a repeat unit of formula III and a repeat unit of formula IV wherein Ph represents a phenylene moiety; each X independently represents an oxygen or suphur atom; n represents an integer of 1 or 2; Y is selected from a phenylene moiety, a Ph-Ph moiety and a naphthalenyl moiety; W is a carbonyl group, an oxygen or sulphur atom, Z is selected from —X-Ph-S02-Ph- —X-Ph-S02-Y-S02-Ph- and —CO-Ph-; b) melting the feedstock material; and c) extruding the feedstock material to form a plurality of parts that define the object.