An electromagnetic shield structure (100) has an elongated conductive wall (102) that continuously or discontinuously defines a shielding perimeter and has a flange (104) laying over laterally to form a J-shaped hook (106) in cross section. A conductive cover or lid (108) engages over the standing wall (102) and has a depending side wall skirt (110) that has a flange (112) and forms a J-shaped hook (114) facing opposite from the hook (106) of the elongated wall (102). The cover (108) is pressed onto the wall (102) for assembly, causing the flanges (104) and (112) to deflect and snap over one another in the space between the overlapping skirt (110) and wall (102). The shield enclosure (122) can be disassembled without damage by applying a tool (116) through an opening (118) in the outer one of either the skirt (110) or wall (102), to deflect and disengage the flanges (104) and (112) in the space between the overlapped skirt (110) and wall (102).