I have been using a Soarer's Converter for my IBM Model M keyboard. The converter was made from a Pro Micro board and I originally built a small wooden box for it. But the lid of the wooden box could no longer stay on after years of wood drying and shrinking. So I designed a 3D printed box for it. The box has two holes on each end to accommodate a USB cable and a PS2 socket cable. The lid snaps in place.