The inspiration was the Jron2008's WhoopDegen case (https://www.thingiverse.com/thing:6572641), but it was too big for my taste.

But then I found the CH26's design (https://www.thingiverse.com/thing:6734248), but it was for 75mm, so I decided to try to dig around and resize it myself.

I resized the case to fit a 65mm whoop, changed the LiPo system to fit a 12 LiPo, and shrunk the two side "boxes". Also I've removed holes that CH26's design had.
Quoting CH26 - “The latches and hinges are held in place with 20mm M3 screws. You need 8 screws in total.”

I've remixed ledoc95 latch design, (https://www.thingiverse.com/thing:4142209). It has longer "handle", but still pretty hard to open the box. So I made it lil bit longer.

If I find time I will try to make the case even smaller and put the LiPo under/above (with some kind of shelf?) whoop.

Hinges and latches uses M3 screws, you will need 8 of them. If you want to trust only screws, use M3x20mm, if you want to put nuts on them - M3x25mm.