I created a hardware design that can drive up to 320 mA at 3.3 V when using one AA, and up to 750 mA at 3.3 V when using two AAs. The output is convertible to 5V just by placing a jumper. It has a low battery GPIO output that you can monitor with your particle to let you know when the batteries are getting low, allowing you to go into a lower power mode or to just send a message to replace the batteries. It also plugs right into solderless breadboards and perf boards for prototyping.
I think it’s perfect for the Particle community - just plug in the batteries and go. It’s Creative Commons licensed and I put all the design files up on my Hackaday project page, so you can build your own if you’re handy with hardware:
If you don’t want to build one, there’s still time to preorder from the first batch that will be built on the Kickstarter campaign.