The present invention relates to a shell assembly for a medicament delivery device (14), which shell assembly comprises at least one first shell section (12 102) provided with an entry passage (18 105) and designed such that at least a major part of a medicament delivery device (14) entered through said entry passage (18 5) is accommodated inside said at least one first shell section (12 102), a closure element (38 104) operably arranged to said at least one first shell section (12 102) for closing said entry passage (18 105), and fixation elements (20, 32, 34, 48, 54, 8 106, 108, 116, 122, 126) arranged for fixating said medicament delivery device (14) in relation to said at least one first shell section (12 102) and said closure element (38 104).