Bobert, this "trick" does not have to be done on a twelve string. A good shop may be willing to sell individual strings at guages matching the sympathetic strings in a 12 string set, or just buy a 12 string set. Just string up yer guitar with just the sympathetic strings, and, voila, you have a completely new and different instrument. If I remember, the G string becomes the highest note of the six. It makes for a wonderful sound, and be sure to try a capo at maybe the 4th or 5th fret. I love to fingerpick with this set up. The high lonesome sound. I have seen this technique referred to as "high-strung" guitar.
As for a 12, there is just nothing like that jingly jangly sound on some songs. Fingerpick, flatpick, or strum can all do just find on the right songs. I fell in love with a custom Santa Cruz 12....a Model H (small body, but deeper than most), koa top, sides, and back, 42 style inlay, and she sounds like a cathedral.

dw