I made my own portable phone charger, and I didn't electrocute myself - The Verge
Amazon.co.jp: 18650 Battery Charger Box, Portable 8x18650 DIY Mobile Power Kit, DIY Power Bank 18650 Case, LED Flashlight, Phone Tablet for USB Devices (Blue) : Electronics
Open source Lithium battery charger modules
DIY Solar Mobile Charger / 18650 Battery Charger - Hackster.io
2x18650 Usb Power Bank Battery Charger Case Diy | Power Bank Diy Phone Charger - Instrument Parts & Accessories - Aliexpress
Amazon.co.jp: zmart 8x18650 Mobile Battery Bank Box Power Cell Phone Charger DIY Shell Case Power Bank Holder Case Dual USB LCD Digital Display Storage 8x18650 Mobile Battery Bank Box Power Cell Phone
Make your own portable phone charger with a BATTERY! (Demo) - YouTube
DIY Mobile Battery Charging Station for Workshop
Portable 2 Ports USB Power Bank Case DIY 3x18650 Cell Phone Battery Charger Charger Power Bank Case Kit for iPhone Huawei Drop
Amazon.co.jp: DIY Power Bank Box, 18650 Battery Charger ABS White Type-C Wide Application LCD Display Cell Phone 22.5W Fast Charging : Electronics
Mobile Power Bank Power Station Case Battery Charger Box 5V 2A 1865O USB DIY | eBay
Universal Phone Battery Charger DIY - YouTube
How to make a DIY Power Bank with 9 Volt Battery
DIY USB Battery Charger for Cell Phone Lithium Ion Batteries From a Wireless Mouse Charger : 4 Steps - Instructables