Bone Conduction Speaker Pen w/Bluetooth

The pen is able to conduct audio from a smarthphone directly to the inner ear via the bones of the skull simply by biting on the cap. The sound is barely detectable only a few inches from the ear, but when pressed onto the teeth it becomes clear and loud. It works with individuals with normal or impaired hearing, and can be used without blocking outside noises as most conventional headphones do. The most expensive part of the build was the audio transformer, at just over $11. The plastic for the body of the pen is recycled milk cartons that were melted back into stock that could be turned on the lathe. The steel came from a large bolt. Link for CAD model: https://drive.google.com/file/d/0B24paL_kGbrbNmp0dDZtUllLX0U/view?usp=sharing Links for electronics: https://www.digikey.com/product-detail/en/tamura/MET-23/MT4148-ND/285665 http://www.ebay.com/itm/Wireless-Bluetooth-4-0-Stereo-HeadSet-Handsfree-Earphone-For-iPhone-Samsung-LG/162597953661?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D45703%26meid%3Def75cb62af204b5793f1b9b16a0943ae%26pid%3D100005%26rk%3D6%26rkt%3D6%26sd%3D122178302461&_trksid=p2047675.c100005.m1851 https://www.amazon.com/Vktech-Trigger-Acoustic-Pickup-Guitar/dp/B016CW1WK6/ref=sr_1_1?ie=UTF8&qid=1502149884&sr=8-1&keywords=piezo+disc