A while ago, I've made one for myself. It took one usb otg cable, two lego bricks, three card-readers (couldn't find the good one), some soldering, some glue and couple hours. Here's how it looks like:
Sony Xperia Z1 C6903 | 14.3.A.0.757 Android 4.4.2 | BL Unlocked | DoomKernel v21 | Integral Micro SDHC 32GB
Please consider a donation if You like what I do Donate
XDA Developers was founded by developers, for developers. It is now a valuable resource for people who want to make the most of their mobile devices, from customizing the look and feel to adding new functionality. Are you a developer?