I have one of the "Fielding solution" capo's that Rick modified for me the last time I was in Toronto. It is for a 12 string. It is a "Paige" style in that it is a u shaped capo, with the pivoting bar that goes across the strings and has a hasp to hold it. Then you tighten the knurled nut from the bottom. Key to these, whether Paige or other manufacturers, is to place it close behind the fret and tighten it only as much as is needed to produce a clear note on all strings. I often see folks tighten them down so hard it takes pliers to get it off. Close to the fret allows one to get the clear tones with minimun distortion of the string shape. Rick filed grooves in it that correspond in width and depth to the appropriate string. I must tell you that it is the best capo I have ever put on a 12 string.
There is such a disparity in string sizes on these instruments that the idea that a uniform pressure across the strings, while it may be adequate, will not give you optimum performance. Rick's solution is the best I have seen.
All the best,