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The Shouldered Scorpius is a variation of the Spider Slider, one of the first puzzle made by Stewart. There are three versions.
In the first (166A), there are three kinds of pieces. It disassembles into two halves along a single sliding axis. he three pieces in each half are dissimilar and go together one way and in one order.
In the second (166B - shown here), all of the pieces are identical, but non-symmetrical. It is a coordinate motion puzzle, difficult to assemble and near as difficult to disassemble. I was not able to disassemble it by working the pieces apart, even when spacer were placed between the pieces. Spinning will get it apart in an instant, but trying to spin it just a little and have a look at a half-disassembled puzzle was unsuccessful. Very frustrating!
In the third (166C), all of the pieces are identical and symmetrical. It is easy to take apart - once you know how (quoting Stewart). Putting it together is another matter. Like the second version, it is a coordinate motion puzzle. As noted, number 166B in Stewart's numbering system.