This case was designed for http://cyberstalker.dk/finalkey/
There is room for a 3 mm LED, a 6x6 mm tact switch and Micro USB connector.
There is no back-plate, the intention is that cavities are filled with epoxy or hot-glue to protect the device from the elements and to give it strength and stability. The hot-glue approach have been used by myself several times, all with success, and works perfectly, the "high" temperature of the hot-glue is not a problem for the components or case material. You need a tact-swtich of the "tall button" type. The led may be pressed into place using a small flat-head screwdriver. With the non-black/white cases, you may need to gently remove some of the material in the holes which seems to be a byproduct of the polisihing process.
If you are interested in an assembled and ready-to-use Final Key, contact me using the e-mail address on that website..