After recovering from turkey coma's and holiday festivities, I managed to do a bit of soldering recently. I had the need for a LIR2032 coin cell charger to power a few projects. Unfortunately (or fortunately depending on how you look at it) , the charger I had ordered off Amazon didn't work, so I decided to build my own. I took the guts of the Solder Sniffer 9000 project, which consisted of a MCP73831 for the charge controller, and modified it a bit to charge an LIR2032.
The main change needed was the value of R3, which is responsible for setting the max charge current. For the LIR2032, the max charge current is 35mA. By using the supplied formula in the MCP73831 datasheet (I = 1000V/R) I was able to find that a 28K resistor would give me the charge current needed.
To get a decent connection to the USB socket, I tinned each of the pads a bit.
Here's a picture of it in action.