In the state where a handle (2) and a lid (12) are attached to a main body (11), left and right bases (22) of the handle (2) are fitted into recesses (1112, 1113) at coupling portions (111, 112). Left and right shaft supports (91) of the lid (12) are fitted into recesses (1111, 1114). Shaft portions (81) of the left and right bases (22) are fitted from above into a through hole (72) and a through hole (73), respectively, and are supported rotatably about a center axis (200) in the through holes (72, 73). Shafts (93 to 95) of the shaft supports (91, 92) are laterally fitted into through holes (71, 74, 75), respectively, and are supported rotatably about the center axis (200) in the through holes (71, 74, 75). The shaft (94) of the shaft support (92) is laterally fitted into a blind hole (82) of the right base (22).