I've been thinking a lot about health lately, thanks to Clairvoyant's health challenge. And I've been reading about the health benefits of a standing desk (or maybe not). You can buy standing desk converters like these:

But they start at $75 & they don't look great, so I decided to build one. I prototyped it with stacks of books and came up with a 12" rise for my keyboard and a 20" rise for my laptop on its mStand. The mStand isn't required, but I use it when I'm sitting so it might as well stay. 18" wide is enough to hold a keyboard and trackpad comfortably.

I built it out of some 3/4" cherry ply I had leftover from the desk. I routed the edges so they're rounded and I put a brace at the top of the back to hold everything square.

If I were to build it again, I would change some things:

move the legs in about 3/4"
have shelves overhang the riser by about 3/4"
blend the roundover more carefully into the lower shelf
use a wider brace so it's more certainly square

But that stuff is minor. I'm pretty pleased with it.