A few nights ago I managed to break the slot which holds the SD card on my Raspberry Pi. A stupid move: I tried to take it out of its (very nice) Adafruit case without first removing the SD card. There are two delicate flanges on either side of the card slot which hold the card against the connection pins. A millimeter of thin plastics separates you from an RPi which works and one that doesn’t.
The fix: (i) cut off a strip of scrap metal that fits over the underside of the card holder — about 15×29 mm. You can cut metal with a Dremel and a carbide disk. Be sure to use safety glasses! On my first attempt, a disk broke and a piece went flying into my face just above my left eye. I wear glasses, which saved the day. However, glasses are really not adequate projection. (ii) Glue the strip of metal to the SD card holder with Gorilla Glue or some such. Be careful not use too much glue — it will drip into the SD card holder and keep the card from seating properly. (iii) Clamp the strip in place and wait one hour. (iv) Test. You may have to place a little piece of folded paper or stiff plastic folder over once in the slot between the card and the metal strip if the card does not seat itself tightly against the metal connectors.