Use a UV/weather resistant filament. I suggest ASA-CF, PC-CF or ABS-CF. PETG-CF is UV resistant to some degree (better than PLA). 

Designed to be used with the LWS category of camera rails/rods. the rods are 60mm apart and have a 15mm diameter.

The battery slot in this model is 73.2mm*22.0mm, which is perfect to fit this common 26800mAh battery from Amazon:
https://amzn.eu/d/07SdJV7i

when printing with a fibre-reinforced material, the fit on this model will be much better than PLA too.

I recommend turning on tree supports for the battery holder:
 

 
Hardware:
- 1/4 inch heatset inset (8mm outer diameter, any depth):
https://uk.store.bambulab.com/products/round-threaded-brass-heat-insert-nut?id=599006975854325762

- Quick-release 1/4 inch screw:
https://uk.store.bambulab.com/products/1-4-camera-quick-release-plate-nut-2pcs

alternatively, these parts could be glued together.