I prefer to stand while working, and have built several standing and treadmill desks. While they were functional, my previous standing desks have really been hacks, using whatever scrap and random hardware I had at hand. Once functionally finished, I never aesthetically finished them, and simply starting working on them. I recently had the need to built a new standing desk, and took it as an opportunity to learn from my previous versions, build from some very nice walnut hardwood, and to properly finish it.
Step 1: Design
With access to a nice shop for building and assembling and little necessity to hand write, the desk with my computer has changed from a work surface to a surface to hold my keyboard and a surface to collect junk. With this in mind, I designed my desk to minimize the actual desk surface, hoping to keep the accumulation of junk in check. It's really more of a small shelf with a keyboard tray than a desk. It's just deep enough to hold a laptop, and the other dimensions are generally based on the Golden Rectangle.