The original board was too large. So I redesigned it to be about 12mm x 45mm. I can get a panel of 12 of these for about 3$ and cut out the individual units myself. So that's about 0.25$ per board which is pretty good!
The battery holder extends past the board. Not much I can do about that!
The light and tilt switch can be soldered directly in, or attached via JST header. There are also 2 spots for a current-limiting resistor for the LED, in case I want it brighter but don't have a 500 ohm 0402 resistor around (closest I usually keep in stock is 1k).
Near Q1, there's also a junction that connects the signal out to an optional MOSFET -- designed to control at most 2A of current. In this case, the power supply is not a CR2032, but something else soldered in, and the light is connected between VCC and the extra pad just above the transistor. This way the circuit can be used to make a powerful flashlight as well as a nightlight.
One small thing I could have done better -- I designed it as a single sides PCB to save costs. However, the cost different is minimal, and the manufacturer doesn't plate the holes in the board if it's single sided! This makes the connections less mechanically robust, and presents fewer options for how the board can be populated (presently through-hole components can only be populated from the verso).
Given the minimal cost savings, future revisions of the board should use double-sided board even if it's unused. Although perhaps I can think of additional features to put there, e.g. a TP4056 lithium battery controller or a spot for a full-size MOSFET.
One neat thing! The manufacturer seems to have put a thicker layer of solder mask on this board (as well as on the other unrelated boards I ordered at the same time). This actually really makes them look and feel high-quality. So if any manufacturers out there are listening, it's a bit of a value-add!
