If the camera still reads the card, the safest first step is to copy everything off using the camera’s USB connection or Eye‑Fi/Wi‑Fi transfer. Do that before attempting any repair.

A broken SD shell is sometimes repairable, but it’s delicate. One community suggestion was to carefully split open a scrap SD card and use part of its shell to rebuild the damaged card, transferring the internals and gluing the shell together. This is risky: the internal connections are very fine, and you could easily destroy the card entirely. A 3D‑printed shell is unlikely to be ideal because SD cards need fairly tight tolerances.

If your Mac reader has damaged cards before, stop using it. The break point described is not normally where the slot’s locking mechanism grabs, so the reader may be damaged or have debris inside. Use an external card reader or transfer through the camera instead.

In short: recover your files first, avoid the faulty reader, and replace the card unless you’re only attempting a careful repair as a last‑chance data recovery measure.