These case corners have been designed with FreeCAD 0.17. Four different FreeCAD files for plain, footed, holed, holed and footed corners. Open the file, adjust the parameters in the 'Dimensions' spreadsheet and generate your customized corner. As some parameters combinations are impossible, FreeCAD will either ignore your choice or just crash. Feel free to use and share this design. Good design is hard work, donations are welcome