After building the first revision, there are several mechanical and footprint issues to be addressed in rev 2. There are no electrical issues so the schematic will remain unchanged.

I've verified the following features of the design:

• Power over USB
• Battery Charging over USB
• Under Voltage battery cutoff
• Battery Charging
• PWM fan control at all speeds

There is a slight issue with the battery dimensions such that the battery contacts the work table rather than the edge of the PCB as intended. In the rev 2 files the board has been extended 2mm to remedy this. 

In order to create a stable stand, I've used one populated PCB along with one blank PCB to hold the fume extractor upright.

Rev 2 has no additional features to rev 1, some features which may be implemented later include:

1. Smaller potentiometer, current one is very tall
2. LED to indicate power is on, it's so quiet it's easy to forget
3. Higher power charging
4. Support for larger and smaller fans