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"NOKIA BL-4C" by IWSE Zhang
(cdna.artstation.com)
Source: NOKIA BL-4C (by IWSE Zhang - ArtStation)
ArtStation profile: https://www.artstation.com/iwse
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Just keep in mind you'd be working up a sweat for hours and hours to charge that.
And we'd all be healthier for it!
But you could do it, which would give it a use in remote areas with poor electrical service given the ubiquity of both USB power and the BL-4C battery.