A X-Frame (also known as St Andrew’s Cross) got its name from its shape identical to the letter X. The X-Frame is usually mounted against the wall, but free standing versions exist as well. To restrain a person, the X-Frame usually has cuffs for both arms and legs, forcing the subject to spread arms and legs, making the position ideal of many forms of punishment. The cross, especially when standing free, is often reinforced by a set of horizontal bars.
Sometimes, instead of being stationary against the wall, a center bearing so the subject can be turned upside down.
Building a simple wall-mounted X-Frame can be fairly easy. The most basic form is simply two 2×4 or 2×6 boards (5×10 or 15cm). To mount them against the wall, mount first one side securely, then use two smaller 2×6 pieces to mount the other side. Of course, this form of an X-Frame is off balance by the thickness of the wood chosen. To compensate for that, many people simply cut the second board of the X, covering the cuts in the center with leather that can double as padding for the hips. Most complex but still fairly easy is creating a notch in both boards of half the depth of the board (thicker boards like 4×6 (10x15cm) recommended if you’re not experienced in working with wood). This can easily be done by laying the boards across each other on the floor and marking where they meet. Then measure half the depth and take out the remaining wood with tools like hammer and chisel. After putting the cross together, you should use screws from the back to hold the two boards together.
A free standing X-Frame is more difficult to build. Thicker boards are recommended for stability. Also, if you are using the notch approach, you can use some hurricane straps found at hardware stores to reinforce the center of the cross. Next are the stabilizers for the frame. Usually a free standing X-Frame is leaning forward. Often you see this done using a third board 2×4 (5×10 cm) running into the center of the frame but the author of this article prefers attaching a second X-Frame identical to the first to the top - adding the stability and allowing two subjects to be restrained at the same time. Again the connection is best reinforced using hurricane straps. If you are going to add foot rests to your frame (highly recommended, especially for free standing frames) create an L shape out of 1×4 (2.5×10 cm) wood. Hold it against the frame to measure the distance between the bottom of the L and the ground. Cut another piece of board to support the L and finally add a fourth piece on one side to keep the foot from sliding off. Make sure the foot support is at a right angle to the frame (or even tilted inward) for best support. As always with wood working, make sure to sand (and probably finish) the final product carefully to avoid splinters.