As with many things, it is possible to make an invisible earphone set out of stuff you may have lying around the house and materials that are easy enough to source online. For an easy-to-follow instructional video below.
The method relayed here has been taken from Frank GuYun of Instructables.com. Links to the original article have been provided. In order to follow the process completely, you’ll need to follow both his technical schematics and his instructional video. This answer will work best if you relate to it as a companion piece, or ‘checklist’ if you will.