This is based on the solar minty on the blog. I used Mattel Juicebox for the case. It employs two 2000 mAh LiPo batteries switched out alternately with a DPDT switch, plus a power switch between the battery subcircuit and the Mintyboost (some time ago I measured quiescent current in a Mintyboost and found it quite a bit higher than expected, so why not).
The sun had set by the time I finished but the solar panel does work pretty well to charge the LiPo batteries!
The USB port is a little crooked but OK for now (I ran out of hot glue). I should probably label the ports and switches too.