I'm done with the project to make the Spotify Carthing a desktop and mobile device! I added a few things to the design to make it better for my needs. STL and accessories can be found below.
Thingiverse link:
https://www.thingiverse.com/thing:5818454
Battery Bank:
https://www.amazon.com/dp/B082ZVBTG6?ref=ppx_yo2ov_dt_b_product_details&th=1
right angled USB Type C to USB cable
https://www.amazon.com/dp/B01N32UM0Q?ref=ppx_yo2ov_dt_b_product_details&th=1