With a few supplies and some careful cutting and pasting, you can build the gravity-defying structure that won the 2010 Best Illusion of the Year Contest. Created by Japanese mathematical engineer Kokichi Sugihara, the magnetlike slopes illusion is cleverly designed to make marbles roll "uphill." It's a trick of perspective: The slopes actually tilt downward, but they are supported by leaning columns that look straight when viewed from a specific vantage point. Sugihara discovered the illusion accidentally while feeding 3-D line drawings of "impossible" objects into a computer program designed to interpret them as solid structures. To build your own magnetlike slopes, print out the instructions below, download the patterns, then watch this slide show to see some of the steps in detail.

» View a slide show that illustrates how to construct this attractive deception and see the video below of the illusion in action

Do-It-Yourself Illusion—Instructions for Creating Magnetlike Slopes

Want to make marbles roll uphill? Follow the steps below to create a gravity-defying illusion that won first place in the 2010 Best Illusion of the Year Contest. Kokichi Sugihara, a mathematical engineer at the Meiji Institute for Advanced Study of Mathematical Sciences in Kawasaki, Japan, created the illusion.

1. Get ready. Assemble the supplies you will need to create this illusion:

• Computer printer
• 1 sheet of letter-size copy paper
• 4 sheets of letter-size heavy paper
• scissors
• ruler or straightedge
• metal paper clip
• glue
• 4 small marbles

2. Print.
Use your computer printer to print out these instructions and diagrams on copy paper. Print the four pattern pages on heavy paper, preferably card stock or poster board. (Heavy photo paper and letter-size sheets cut from manila file folders also work fine.)

3. Cut. Using sharp scissors, cut around the edges of each pattern to separate the 11 individual pieces you will need for the illusion: base, five columns (C1–C5) and five slopes (S1–S5).

4. Score. Using a ruler straightedge, score each of the pieces along the lines printed on them, with one exception: Do not score any of the lines that form squares with dots at one corner. Score the lines by pressing lightly with a scissor blade or X-ACTO knife along the straightedge, or by pressing hard with the curve of a paper clip. (Rub the paper clip back and forth along the straightedge repeatedly to create a groove in the heavy paper.)

5. Fold. Fold each of the pieces along the scored lines. For each slope, fold the two long edges and the shaded tab upward, leaving the printed square hidden on the bottom side. For each four-sided column, fold along the sides, and also along the edges of each shaded tab. The columns should be folded so that the printed lines are visible on the outside of each column.

6. Glue. To join the two edges of each column, spread a thin, even layer of glue on the long tab along one edge and paste the tab to the other edge. It is fine to leave the tab showing on the outside of the glued column; it will not be visible in the illusion. You can use an all-purpose glue such as Elmer's or a "tacky" craft glue that allows you to make adjustments while the glue hardens; either works fine for this project. Once you have the column edges lined up perfectly, allow the glue to dry. (If you find it difficult to work with glue, you can use transparent tape instead.) The five completed columns will lean at different angles, ranging from a slight lean (C3) to a severe lean (C5).

7. Match. For columns C1–C4 glue each column to its corresponding slope. For example, glue column C1 to slope S1, C2 to S2, and so forth. (Do not glue C5 to S5 yet.) Glue the column to its slope by attaching the two tabs at the top of the column to the square printed on the bottom of the slope. The corner where the two sides of the column meet (and the long glued tab is visible on the outside of the column) should be positioned at the corner indicated by the dot on the printed square. Do your best to match the top of the column to the printed square. Columns C1 and C2 should extend partly beyond the outside edges of slopes S1 and S2. Let the glue dry completely before proceeding to the next step.

8. Assemble. Attach each column–slope pair (for example, the conjoined C1 and S1) to the central S5 piece by gluing or taping the tab on the end of the slope to the printed side of S5. The edge of the slope should align with one edge of S5. Repeat this for the other three column–slope pairs so that each side of the square S5 is attached to one of the four slopes. After the glue has dried, fold slightly along the four edges of S5, so that each attached slope angles slightly downward toward the center.

Glue column C5 to the base at position 5, using the four tabs on the bottom of the column. The glued edge of the column (where the long tab is visible on the outside) should be positioned at the corner indicated by the dot on the base, and the column should lean at a steep angle.

Finally, position the bottom of S5 (the central square) over the top of C5 (the leaning center column), with the other four columns positioned where indicated on the base (for example, with column C1 at position 1, C2 at position 2, and so forth). Glue S5 to C5, using the square printed on the bottom of S5 to align it with the column. Glue the remaining four columns to the base, using the tabs on the bottom of the columns. The columns should lean, and all four slopes should be almost horizontal with a very gentle tilt toward the center.

9. View. To see the illusion, rotate the structure until you find the viewpoint from which all five columns look parallel. (The corner of the base between columns C3 and C4 should be closest to you, and you should be looking downward toward the illusion.) Now you are ready to amaze your friends by releasing marbles at the end of each slope, and watching them roll "uphill" toward the center. The illusion works best if you keep one eye closed while viewing it. You can also demonstrate your illusion by making a videotape. Looking through a camera is like looking through one eye, so your friends will not need to close one eye when they watch your video.