A method of bonding a connector to a first object and a second object, comprising: - providing the first object with a first opening, the first opening being a through opening; - providing the connector, the connector being separate from the first object, the connector comprising a thermoplastic material; - providing the second object with a second opening, the second object being separate from the connector, the second opening being a through opening; - arranging the first object, the second object and the connector relative to one another so that the first and second openings (11, 12) are aligned and the connector reaches from a proximal side through the first opening distally into the second opening; - using a source of mechanical vibrations to generate vibrations, and applying the vibrations and mechanical pressure to the connector until, under the effect of the vibrations and the pressure, a flow portion of the thermoplastic material is liquefied and caused to flow sideways radially into an open space, wherein the open space is distally of the second object; and - removing the source of the vibrations and causing the liquefied thermoplastic material to re-solidify; - wherein after the step of removing, the connector comprises a foot portion, a head portion, and a shaft portion between the foot portion and the head portion, the shaft portion extending along an axis through the first and second opening, and thereby securing the connector to the first and second object; - wherein the step of applying the vibrations and the pressure comprises pressing the connector against a passive, non-vibrating counterelement with a mould feature, defining the shape of a foot portion, and coupling the vibrations through a proximal coupling-in face of the connector and transmitting the vibrations through the connector to a distal end face of the connector; and - wherein the flow portion forms at least a part of the foot portion, characterized in that the connector in an initial state comprises the head portion, the head portion forming a distally facing shoulder that forms a stop when the connector is inserted from the proximal side into the aligned first and second openings, or in that the method comprises the step of forming the head portion after forming the foot portion. - providing the first object with a first opening, the first opening being a through opening; - providing the connector, the connector being separate from the first object, the connector comprising a thermoplastic material; - providing the second object with a second opening, the second object being separate from the connector, the second opening being a through opening; - arranging the first object, the second object and the connector relative to one another so that the first and second openings (11, 12) are aligned and the connector reaches from a proximal side through the first opening distally into the second opening; - using a source of mechanical vibrations to generate vibrations, and applying the vibrations and mechanical pressure to the connector until, under the effect of the vibrations and the pressure, a flow portion of the thermoplastic material is liquefied and caused to flow sideways radially into an open space, wherein the open space is distally of the second object; and - removing the source of the vibrations and causing the liquefied thermoplastic material to re-solidify; - wherein after the step of removing, the connector comprises a foot portion, a head portion, and a shaft portion between the foot portion and the head portion, the shaft portion extending along an axis through the first and second opening, and thereby securing the connector to the first and second object; - wherein the step of applying the vibrations and the pressure comprises pressing the connector against a passive, non-vibrating counterelement with a mould feature, defining the shape of a foot portion, and coupling the vibrations through a proximal coupling-in face of the connector and transmitting the vibrations through the connector to a distal end face of the connector; and - wherein the flow portion forms at least a part of the foot portion,