iPod classic 160gb modded to 256gb with 2000mah battery and Bluetooth. Just waiting on a 3d printed back. All fits within a thin shell. Very happy with how it's come up. :
Amazon.com: Replacement Battery for APPLEE 616-0232 iPod Classic 160GB iPod Classic 120GB iPod Video 60G iPod Video 60GB MA003 A iPod Video 60GB MA003CH A iPod Video 60GB MA003DK A : Electronics
1 x 650mAh 3.7V Battery For iPod Classic Gen 6th 7th 80GB 120GB Thin 160GB for iPod 5/5.5 Gen Video 30GB 616-0229 battery - AliExpress
bought this ipod classic 160gb from a guy who keep it stored for 10 years, believe it or not the battery seems to be okay, currently playing for 18 hours straight (mix
Replacement battery with tools for ipod classic 6 6th gen generation 160GB A1238 | eBay