These are a pair of storage boxes designed to store the additional small parts that come with the Mavic Mini Fly More Combo.

Box 1 fits under the charging hub in the Fly More case, and holds:
1 Prop Screwdriver provided by DJI with the Mavic Mini
3 Micro USB cables (Lightning, USB-C, Micro USB) provided by DJI with the Mavic Mini
2 USB cables provided by DJI provided with the Mavic Mini and the Fly More pack
2 Controller sticks provided by DJI with the Fly More pack
1 SD to MicroSD adapter provided with many SanDisk MicroSD cards
1 Micro USB OTG to USB A Adapter (generic, available from places like ebay)
1 MicroSD, in addition to any space in the MicroSD Adapter
1 Strobe (provided by Flytron), without its mount.

Prop Box fits under the controller, and is designed to hold the additional spare props that come with the Mavic Mini and the Fly More Pack. Additionally, I also use it to store more lens cloth and a OTG lead.

Box 1 purposely has a lip around the top of the area where the 2 USB cables are stored, this helps keep the USB cables in place in the box.

The lids are TPU, and are designed to be a reasonably tight fit, relying on TPU's flexibility to hold it firmly in place.

Doesn't Matter

No

Doesn't matter, I used 0.1mm

10%

Box bases are standard PLA, box lids are TPU