I used PETG at 240/80 but also made a few w/ PLA and they were fine either way. I Just liked black and I only had PETG in black. I used supports only touching bed for the case and the end cap. Nothing on battery tray. I made this modular and used 3MM brass threaded inserts to secure the battery tray to the end cap and endcap to the case. One 3mm screw holds the endcap/battery assembly into the case. I also used AA spring contacts which will have a very good friction fit. Just solder your connections and go. I used spade connectors for one battery to external contact config and eyelets for another, either way will work. Pics are before I inserted the case to endcap brass insert.

Spring contacts
https://www.amazon.com/dp/B0B1ZJ8PNH?psc=1&ref=ppx_yo2ov_dt_b_product_details

Brass inserts
https://www.amazon.com/JROUTH-Threaded-Assortment-Printing-Injection/dp/B0CH82LQS9/ref=sr_1_3?dib=eyJ2IjoiMSJ9.-fhcK4Br63JKIa4Bq34E2pnc1QzWVFrVvoO7Za2-LkeBqYS5cn1yPQCslmG_HdvEpug8JqbNQB0ftGwcx7vP6IxTrOol5-AP0o5AG3VliPHCyHkDQMiT_3Rh6vSm7eTngexGp1pJJae3Z63eKTs146F3ZRSSqWyTLC_dBNCt7YAU9u3dHq25aeggTNMyFxl4PD1dEbOFDo0NJBVJ3U-9maRVd8VTOnC8lUpqIwmQvtI.iY6v214GUYNbY8Hyvzabx3j20nvfumdtrTiEUoXUK8Y&dib_tag=se&keywords=3d+print+brass+inserts&qid=1712421786&sr=8-3