Nintendo 3ds (CTR-001, 2011) Battery Extender Cover

Allows the Installation of another larger battery inside the 3ds. The original cover is reused but has to be glued on with double sided tape. I recommend using the thinnest available. The extender frame can still be removed with a very thin screw driver that fits through the back cover screw holes.

Maximum battery thickness is 5mm.
Maximum recommended battery size is 50x110mm.
Battery Type is Lithium Polymer 3.7V but 3.8V also works, you lose some capacity.

You can use any phone battery that fits into these dimensions. You must install the battery in parallel to the original battery, not in series! Make sure both batteries have the same or a very close voltage to one another when connecting them to prevent large current flows. The 3ds charge indicator will be wildly inaccurate so you will need to learn the new discharge behavior of the system to know when it shuts off. Mine for example lasts about one hour on "1%" charge.

Tolerances are tight, use outer walls first when printing.
Nozzle: 0.4mm
Layer height: 0.2mm
Support: Yes (Classic support)
Material: PLA
Seam alignment: Sharpest corner, hide seam

Based on the 3ds Battery Cover by @OhYou_
https://www.thingiverse.com/thing:4785061