Battery powered WS2812b Project - Help Selecting Battery and Regulator

Hello,

I am working on a project that will use a 1-meter length of 5V WS2812b LED strip with 144 LEDs in total. It will be used as a light wand, and will have the potential for all LEDs to be full on. At 60 mA per LED, this is a potential for 8.6A total draw. I know it will most likely not be this much, but I wanted to engineer for the max current requirement.

The project will have a 3d printed handle, and I was hoping to fit the power source along with the PCB (yet to be designed) into a flashlight sized handle. I could potentially design it to fit 8 AA batteries or some other battery pack made from rechargable batteries. Most linear regulators that I have found to create a regulated 5V source are low current (3A max).

I'm looking for suggestions for a battery and regulator combination that would be able to deliver the 5V and 9A current or so and fit within the handle I will design and 3d print. Is it better to connect for AA batteries in series and then another 4 in series as well, with both 4-packs in parallel to give me 6V with double capacity? A rechargable option would be preferred. I would be open to creating my own battery pack with rechargable cells also.

The biggest problem that I keep running into is the voltage regulator. I would prefer to design my own into my pcb, and not have to try to fit a pre-made buck converter into my design.

Any help is appreciated. Thank you.

I think I've figured out the batteries. I will use a 2S2P configuration of Li-Ion 18650 cells which will be 7.4V. I just need help figuring how to take that and make a 5V source to power the LED strip and the Arduino. I will design my own PCB, and would put a voltage regulator circuit on it but I cant seem to find anything that is rated for 9 Amps.