If you want a Back To The Future flux capacitor, you've only had two options, build one yourself, or buy the USB car charger (btw very cool). But what about one that you could take with you? The team at Mad Geek Collectibles have created a Kickstarter project for a 1:10 scale replica that can be converted into a keychain.
Because this is an officially licensed product, Mad Geek Collectibles were able to get Bob Gale, Back to the Future co-creator involved with one of the perks, which has already sold out. Gale had this to say about the mini flux capacitor:
“Great Scott! This is the perfect key ring for all BTTF fans, and now I can actually say, ‘where did I put my flux capacitor?’”
This flux capacitor is the most accurate and purchasable replica I've seen. The standard edition is made from a die-cast alloy and a limited edition stainless steel version is also available. There is a button on the back that starts the flux and pressing it a second time will start the time travel effect. The standard edition is available for $28 and the limited quantity stainless steel version is $48. Both editions are expected to ship 2nd quarter 2015, just in time for the 30th anniversary of Back to the Future.