Abstract: The present invention relates to an instrument case including two side panels, arranged to mate with a further panel to be supported substantially parallel thereby and to a member adapted to interlock in a plane normal thereto with both side members to brace the side members. The side panels, the further panel and the member coact to provide a self-supporting structure. The case may be completed by the addition of further panels. The case constitutes a support and enclosure for circuit boards, the member forming a mother-board which may act as a case divider. The case thus formed solves the problem of providing a circuit board support and mother-board without recourse to additional components and a card frame with its consequent weight penalty.