This is a two-sided die of my own design, in my steel 'pepper-pot' line of unusual dice.
To get a random selection of two alternatives, you can of course toss a coin, or roll a larger die with agreement of what the different sides mean.
Under some circumstances however, neither of these is ideal. Larger dice can also repeat faces to give a direct readout of course, but I enjoy the elegance of a single face per result. I have investigated what makes for a good two-sided d2, and this is what I came up with.
When it hits the table, a good die will tumble a number of times rather than sliding. However, it should not roll too far. I started by iteratively trialling various forms in clay to determine rolling characteristics, before testing candidates in Shapeways plastic, and finally improving the parameters of the best one. I am very happy with the nature of this randomiser, and if you buy it I hope you will be, too.