A method of fabrication of panels having built-in heat pipe(s) and/or insert(s) (P), includes providing a bottom plate having tabs, partially straightening the tabs toward the accommodation zones, positioning the heat pipes and/or the inserts in each accommodation zone between the tabs and in contact with the upper face of the bottom plate, terminating the straightening of the tabs, depositing a selected thickness of a first adhesive against side faces of the heat pipes and/or the inserts, positioning separating structures, substantially having a same height as that of the heat pipes and/or the inserts on either side of the side faces of each heat pipe and/or insert and in contact with the upper face of the bottom plate, and placing an upper plate above the heat pipes and/or inserts and the separating structures and in contact therewith.