A Reddit user, Sockpockets took it upon himself to add a MicroSD slot on his 2013 Google Nexus 5 smartphone. To understand why he did you should know that the Android 6 Marshmallow version supports MicroSD cards as internal memory.
Sockpockets took the back cover off his phone, connected a microSD card adapter to the micro USB connector, and now his phone can read removable storage cards.
Since Android 6.0 allows for adoptable storage, he can even treat a microSD card as if it were internal storage, although it won’t be as fast as the built-in storage. He notes on the thread that, While he can successfully access the memory from MicroSD card after the hack, he has had to face following problems :
The back cover won’t fit on the phone while the adapter is connected, so you’ll need to improvise a solution. Sockpockets put a third-party cover on the back, but it doesn’t offer a lot of protection against dust since there’s an opening for the camera. While a USB OTG adapter is connected, you cannot charge the phone with a USB cable. So you’ll need to use wireless charging.
However considering all the odd, Sockpockets did something impressive. If you want to try out the same, do remember, you can damage some functionality in your Nexus smartphone or worst still brick your smartphone.