While I have an Arca Cube for my "big rig" tripod and am quite happy with it, I also wanted a geared head for my ultra-lightweight travel tripod. But of course no such thing exists, so taking my lead from others who contributed to this thread, I assembled one myself and here is the result:
As shown above, the head weighs 5.8 ounces / 165 grams, which is a savings of 2.2 ounces over the ballhead I was using (Benro B00, which is the lightest, decent-performing ballhead I could find) and literally a fraction of the weight of my Cube. It was built using 25mm x 25mm Melles Griot goniometers and a Melles Griot rotational stage (I skipped adding a second rotational stage at the bottom of the stack because my tripod's center column rotates freely, making it unnecessary and saving a bit more weight and cash.) The clamp is a no-name one from China (but after I finished assembling this version last week, I found an even smaller and lighter one on eBay, so will try that once it arrives.)
Unlike most goniometers, the bodies of these are made of aluminum, not brass, hence their light weight. Unfortunately, this also means their load capacity is fairly low, but I'm using them with a Sony RX1 that weighs just over 1 lb. and so far, I've had absolutely zero issues with it. The control knobs would benefit from being a tiny bit larger (and I will investigate my options for replacing them down the road), but even with my large hands, I've had no problem using any of them.
Of course, the other downside is cost: All-in, I spent just under $400 on parts (including some other pieces acquired as part of a package deal -- a single-axis translation stage, a second rotational stage, and an XYZ (three-axis) translation stage -- which I didn't use and are not shown here) and I spent nearly a year acquiring them on eBay and from other internet sources for prices I was willing to pay, so if you're in a hurry, expect to pay more -- and potentially a
lot more, as some sellers are mighty proud of them! -- for the necessary bits and pieces. (Note: There are also 25mm x 25mm goniometers and positioning stages made by other manufacturers and available both new and used, but for various reasons -- typically, they were too heavy or had too low a load limit -- I decided against using them.)
I initially attached the head to the tripod via an adapter plate, but now that I've proved the concept and am happy with how it works, I'm in the process of modifying the tripod's center column so I can mount it directly without using an adapter. Not only will this save an additional .8 ounces, it'll also make for a more rigid, direct connection to the column and provide a little bit more stability to boot. Unfortunately, the required modifications will be permanent -- there'll be no going back later! -- but I've just acquired a second, used tripod as a backup, so I'm okay with this.
Once completed, the final tripod / geared head combo should weigh right around 2 lbs., 2 ounces, which isn't too awfully bad. In fact, my complete travel outfit -- Sony RX1, modified Sony wide-angle converter for the 28mm/f2.8 lens, EVF, four spare batteries, four 32GB SD cards, 3" cable release, 49mm IR filter, microfiber lens cleaning cloth, and a Manfrotto Nano VI belt pouch to carry everything -- presently weighs a whopping 4 lbs., 6 ounces. Ultimately, with some other modifications I have in mind for it, I expect to get the weight of the tripod / head combo to just under 2 lbs. and the total weight of the outfit to 4 lbs., 2 ounces, but we'll see. (Yes, I know saving a few more ounces at this point is silly, but this project has become an intellectual curiosity -- how low can I go without sacrificing performance or ease of use? -- plus I'm presently unemployed, so have time on my hands hence why not?)
So thanks to all for the inspiration! (And if anybody wishes to follow in my footsteps, I'll be happy to answer any questions I can, although I believe this is a fairly simple and straightforward project. Honestly, the only difficult part of it was finding the necessary parts at reasonable prices.)