Martha Stewart shows us how it's done, with a full tutorial on her site. You'll need tooling leather, a leather punch, plastic lacing, and at least one of the four templates available here. (There's an iPad sleeve, wallet, pen case and mousepad).
The combo of leather and bright-colored lanyard lacing seems more modern and trendy than its unrefined arts-and-crafts materials would have you believe. The earthy neutral leather goes well with trendy pops of neon.
If your style is less DIY and more BIY (buy-it-yourself), try surfing the handmade marketplace at Etsy for one-of-a-kind leather cases. We like the one below from J.W. Leathersmith ($55, Etsy.com).
Full instructions: Martha Stewart