So [Travis] decided to upgrade it to make use of the ever-so-common, 18650 lithium-ion battery. Not looking to purchase any components [Travis] performed this hack using simple recycled household ...

By taking a 3D printed design intended to attach a TP4056 module to the end of an 18650 cell and combining it with an ESP8266 firmware that turns the powerful microcontroller into a WiFi repeater ...