The illusion is very similar in principle and performance to the older "Thin Model" versions of sawing a woman in half, with the exception that the boxes used to cover the assistant being divided are clear, rather than opaque. In basic concept, it is very similar to the transparent sawing developed by Les Arnold in the late 1970s. However, in the Pendragons version, the boxes are much smaller, and are never covered at any point during the illusion. As a result, the assistant within the boxes remains in full view throughout, making this a particularly baffling illusion for the audience.
The illusion usually begins with the magician showing the audience a low table, designed to split into two halves. The main assistant is then introduced, and lies down on the table. Other assistants then place two boxes over the assistant, with clear sides and tops. As the upper box is placed over them, the main assistant extends their arm out of the open side of the box, while their head and feet extend out of the ends of the two boxes. Small stocks are then used to restrain the assistant's feet and neck. Because the boxes have clear sides, the audience is able to see right through them, and can see that the assistant has not curled up inside the upper box, as is described in many commonly available magic books for the "Thin Model" sawing.
The magician then cuts through the box using either a saw or sword (although some performers skip this step), and dividers are placed into the box either side of the cut. With the dividers in place, the two halves of the table are unlocked and pulled apart. As the assistant has been in full view of the audience throughout the illusion, it appears that they have been separated into two halves, the impossibility of this situation helping to give the illusion its name. The halves of the table are then pushed back together, the dividers removed, and the unharmed assistant released from the stocks and boxes.
While she was in a relationship with David Copperfield and not otherwise occupied with modelling work, Claudia Schiffer often assisted Copperfield in his stage shows as a "special guest assistant". Part of these shows was a performance of Clearly Impossible, with Schiffer as the assistant being sawed in half by Copperfield.
During the 1996 TV special Champions of Magic, Jonathan Pendragon performed the illusion on the show's host, Princess Stéphanie of Monaco.
While appearing on a local TV talk show during a promotional visit to Japan in 2006, actress Mischa Barton took part in a performance of the illusion in which she was sawed in half by a local magician.
While presenting SM:TV Live, British TV presenter Cat Deeley was the first British celebrity to be sawed in half in a version of Clearly Impossible.
During a promotional visit to Europe, Jessica Simpson participated in a performance of the illusion where she was sawed in half by illusionist Hans Klok, who used a large circular saw to divide her in two.
When she appeared on a Mexican talk show, Penélope Cruz took part in a performance of this illusion.
In February and March 2012, Klok visited the UK with his stage show The Houdini Experience, playing a five-week run. During the press night at the Peacock Theatre in London, he amazed the audience of celebrity guests when he invited actress Louisa Lytton up onto the stage and, without any prior rehearsal, sawed her in half in his Clearly Impossible illusion.
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The assistant's trousers have a rigid frame that locks into place so she can walk normally, but when she is lying down she can pull her legs back and under her. Some performances hint at this and show it when The Twins perform it. If one looks carefully, false feet can be seen being pushed up or down. Assistant wears a large-size dress so that his/her folded feet can be covered by this dress when he/she is in cut position and in one compartment only. The false feet appears from second compartment.
The magician or his assistant performs some secret changes by rotating the table while fixing his or her neck. The audience will never see both blank compartments at a time and the leg portion glass cover is never revealed clearly. Both boxes are wide in center. This helps the assistant pull up his or her leg. There are 2-3 variations in this magic. Expert magicians and assistant can do this without a deceptive table. A fresh assistant may require some adjustable deceptive table. Even if it is clearly impossible, the other side of the box is never shown and neither the audience nor magician can see the top.
Another version of the Clearly Impossible is without the box (No Box At All). This is done with deceptive table and a sliding mechanism. This is similar to buzz saw. First the assistant is placed on table and two metal covers are placed at the center of her body. By some means, magician covers her leg. A mechanism then inserts her leg inside the table and two complete false leg appears on the table and some electronic mechanism vibrates them. While her leg is inside the table, she pulls her leg, but not completely. A triangle type leg structure is formed. Now her body is cut by magician.
Before separating both table, magician pulls her in head end about 1.5 feet. This allows her triangle-formed legs to enter into deceptive body table. Now both tables are separated. The entire action is reversed and magician guards the false leg. In the meantime she makes her leg straight and a mechanism pulls her let on table and vanishes the false leg. There are also two or three variations of this illusion, one with a normal deceptive table and another with folding type deceptive table where initially a box is used but opened afterwards.
- "The Art of Magic". Magic Television. Retrieved February 22, 2012.
- Schneider, A., "A New Clear Sawing", Genii magazine, June 1993 (Vol 56, No 6).
- Moehring, J., "The Century: The Pendragons", Magic magazine, Vol.8 No.12 (August 1999).
- The Pendragons performing Clearly Impossible in Cincinnati 1998 PBS TV Special 
- Bryant, S. "Claudia Schiffer: From Supermodel to Magician's Assistant". Genii magazine, August 1996, (Vol 59, No 8.).
- David Copperfield AskMen.com. Retrieved 26 April 2009.
- Top 10 Celebrity Odd Couples Film.com. Retrieved 26 April 2009
- YouTube clip of performance