This is a case for a sub $50 bluetooth GPS that should work with any android app that supports NMEA protocols, commonly used for lap timing in cars/motorcycles. I designed the case for this and gave input on the wiring for my friend, who gets credit for setting everything up. You can get more details about it and him (aidandj) at the forum thread link posted below. Confirmed to work with the following Android apps: Harry's Lap Timer http://www.gps-laptimer.de/Home.html Racechrono http://www.racechrono.com/ Original forum thread http://www.miataturbo.net/race-prep-75/sub-%2450-10hz-gps-receiver-82941/#post1202669 There are some that will be for sale at this thread: http://www.miataturbo.net/miata-parts-sale-trade-5/10hz-bluetooth-gps-module-cheap-83431/page3/ This is an ongoing design and will change a bit. Plans include changing the design to have acrylic plates on both sides and alternate plates that support adding suction cup mounts to keep the box in place. Update 3/9/15: Adding files for suction cup mounting. These are the suction cups that were used: http://www.amazon.com/dp/B00M8C3Q04/ref=sr_ph?ie=UTF8&qid=1425915195&sr=1&keywords=suction+cup Also changed the design to v2 for the bottom, which replaces the 3d printed bottom with a laser cut plate, allowing you to choose which side is oriented "up" using the suction cup mount. Update 3/17/2015: There is now a test video of the GPS working in a Mazda Miata (you can see it by the rear view mirror). https://youtu.be/7RgIXhPY_k8 Update 3/30/2015: New video of the GPS working on a test course: https://youtu.be/qedQlC9anxEParts List: HC-05 (or HC-06) module with 5v adapter board http://www.ebay.com/sch/?_nkw=hc-05+module+5v RYN25AI GPS Module (Be sure to get one that has an EEPROM) http://www.ebay.com/sch/?_nkw=RYN25AI Adafruit USB Mini breakout board http://www.adafruit.com/product/1764 Alternate: Pololu USB Mini breakout board https://www.pololu.com/product/2593 Double Length 0.1" Pitch Header Pins http://www.digikey.com/product-search/en?x=0&y=0&lang=en&site=us&keywords=S1232E-36 Four (4) 1" long 4-40 screws Four (4) 4-40 Nylock Nuts Soldering the Bluetooth and GPS Together When soldering the Bluetooth and the GPS module together use double long header pins (0.1" pitch) and line up the RX/TX,TX/RX, and GND pins (NOTE: RX and TX are "swizzled", meaning that RX on the Bluetooth goes to TX on the GPS, and vice versa). The antennas for the bluetoth and GPS modules should be facing in opposite directions when they are stacked together. Preparing the USB Breakout Board The holes in the case are meant for a 4-40 screw, so you will have to drill out the mounting holes on the circuit board to make them bigger (1/8" should work).