I absolutely love mini arcades. Generally I think of them being mame cabinets, or possibly those all in one joystick sets modified. This itty bitty arcade cab happens to have a nintendo DS tucked inside. Made by someone who goes by “Button-Masher” on reddit, this is absolutely a piece of art. Look at that miniature coin door!
From their comments, it appears that Button-Masher has made several mini cabinets, with this one being the smallest.
Here’s a few more pics. There are even more in the imgur gallery.