I got a Parrot Rolling Spider for fun. The batteries are 570mAH and the life is under 10 minutes, plus the reviews often mention that the batteries will lose their capacity quickly. Further research into this problem indicated that charging them slowly will alleviate this problem.
I wanted a few spare batteries and a way to recharge them. I decided to DIY a dock for them. I had a handful of spare parts, such as the MCP73831 and plenty of small perfboards. All I needed to do was 3D print something to hold the batteries in place, and this is what I came up with.
More pictures if you continue reading.