Do you want to play a rapid-firing Old Shatterhand with drone batteries? Then this design is for you!-) DJI Spark is an amazing little drone - the only bottleneck is the <16 min. flight time with a single, fully charged battery (my advice: buy at least 3 batteries for enough fun!). In order to shorten the battery swapping time I designed this little belt clip which keeps spare batteries as close to your hand as it is possible! Spark's springy battery locking mechanism keeps the battery in the holder socket properly. The belt clip was designed to fit with belts with 40x5 mm in cross section. My favourite belt is 5.11 Tactical's 1.5" high Double duty metal-free belt so I fitted the clip to match with this one. You can customize the belt clip: the uploaded Fusion 360 CAD file contains two parameters: - h_belt: sets the belt height - thickness_belt: sets the belt thickness for the clip Update #20170724: changed the bottom of the belt clip to make mount/unmount process even easier.