The tools I use when wheelbuilding would be expensive to acquire for only one or a few builds, but very worth it for making lots and lots of wheels.
Here's what I use for initial assembly, in either store-bought or homemade version, a Mulfinger nipple loading tool. If I were building only a few wheels ever, I'd still want to make a homemade one out of some 2.5mm to 1/8" rod by grinding a shallow taper and then shortening it to the correct depth:
Then to take up slack and get every spoke to its same starting point, I use a Problem Solvers Holy Driver. To use, you cut a piece of the next thinner gauge spoke as an adjustable length tip, so the tool kicks out at the same depth every time:
Then to take the spokes up to modest tension, I use a Park Tool SW-0 key, which is the most handy shape and size I've come across yet. This is the spoke wrench I'd use if I only had one:
Then to get the spokes good and tight without damaging the nipples, I use a DT Swiss spoke key, lightly modified to soften the grip edges and make engaging the nipple easier:
For a truing stand, I invariably use some version of the Park Tool TS-2 or TS-2.2, because that's what all the bike shops have around. I've never actually owned my own personal truing stand.
My el-cheapo multi sized spoke key was much easier to use when i taped off all the useless size gaps..
