A method of manufacturing a solenoidal magnet structure, comprising the steps of providing a collapsible mold in which to wind coils; winding wire into defined positions (88) in the mold to form coils (34); placing a preformed tubular mechanical support structure (102, 120) over the coils (34) so wound; impregnating the coils and bonding them to the mechanical support structure by applying a thermosetting resin and allowing the thermosetting resin to harden; and collapsing the mold and removing the resultant solenoidal magnet structure comprising the resin impregnated coils and the mechanical support structure from the mold as a single solid piece.