Yep I saw a German company selling these P2H (phone-to-headset as I like to call them) cases with some SDK as well. This idea from google is not bad at all and

Yep I saw a German company selling these P2H (phone-to-headset as I like to call them) cases with some SDK as well. This idea from google is not bad at all and has the added advantage of most likely better software support, however I would prefer the files for a CNC cutter so I could make one from wood or plastic that way it can be used more than once without the obvious wear and tear of cardboard.