The entirety of projects in the Hackaday.com Coin Cell Challenge are removing energy from coin cell batteries with out giving back. Thievery! Being the kind, fair and generous human being that I am not - and instead out of spite - this project makes use of the abundance of unused kinetic energy in the bath room to recharge your coin cell battery.
1. 3D printing, efficient motors and just about every thing else - and perhaps this would be a more practical concept -- then expand that to the theory of every plumbing joint housing a generator.
2. One point not quite enough volts - motors were to blame - followed in close second by inferior glue and acrylic. It is the thought that counts [wink]
3. Per (2) - the motors were scavenged from vibrating tooth brushes - which one may presume drive very little current while operating at 1.5V - thus removing your plaque is not nearly as an aggressive of a task as is generating electricity to charge a coin cell battery.
4. Always diffuse lighting - especially when you did not. ¯\_(ツ)_/¯