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A Jig is a gauge, pattern, or mold used as a guide to the form of a piece being made. They can be 2 dimensional or 3 dimensional. You do not have to use a jig but using a jig helps you build consistently.

ANY JIGS USED BY THE TEAM MUST BE BUILT BY THE TEAM

2 Dimensional Jigs

Create a 2 dimensional jig by pinning down a design drawing to a piece of cardboard and then place this cardboard on top of a piece of very heavy form or insulation board. Use straight pins or hatpins to hold pieces in place while gluing.
Create a 2D jig by using magnets on a piece of sheet metal. You can find small 1' x 2' pieces of 1/8" sheet metal at most home improvement centers. Small square magnets are available at most hardware and hobby shops. The flexible magnetic strips designed to have business cards glued to them are also useful. Lay your design on the sheet metal and then use magnets to outline your design and hold pieces in position while gluing.
Tape a design drawing under a piece of glass and then tape your pieces to the top of the glass while assembling.
Glue aluminum tubing and keystock to a piece of glass using CA glue to create a 2 dimensional frame for assembling a structure. Square up a piece of aluminum tubing with the side of the glass and glue in place. Use a triangle or square to position keystock (metal bars) in the position you want and glue them into place with CA glue.
As you start building you may want to make some tests using different jig configurations. The structures for DIsigning Bridges were very large (150 grams) when compared to the typical structure challenge (20 grams or less). Initially I created some temporary jigs using only pieces of wood, clamps and triangles to create my jig. The aluminum angle is screwed to a piece of laminate shelf to create the bottom of this jig. The weights are being used to hold pieces in position and to put pressure on the glue joints.
After a while I created a jig using pieces of cut up wood shelving screwed to pieces of MDF board (Medium Density Fiberboard). You can't see it very well in the picture but I put clear tape on the jig around all of the places where glue might seep out of a joint so that i didn't glue my structure to the jig.

3 Dimensional Jigs

At some point you will want to assemble your two dimensional sections into a three dimensional structure. This can be done without the use of a jig by using carpenter's squares, a steady hand and patience. You may also want to create a 3D jig to use in assembling your structure.

The picture on the right shows a variety of materials that can be used to construct a 3D jig.  You can use aluminum tubing or blocks of wood to assemble a jig.

There are lots of options to choose from when creating a 3 dimensional jig. You may decide to make your own using materials such as those shown in the photograph. You should also visit hobby shops and home improvement centers and look for materials that can be used for a 3D jig with little or no modification. Hobby shops have plastic boxes and florist foam in various sizes. Home Improvement centers have blocks of wood in various sizes and shapes. Just remember that the team must create any jigs that you choose to use. This does not mean you cannot use something that you have purchased from the store as a jig. It does mean that if the thing you purchased requires modifications to use as a jig - then the team must make the modifications.

Final Notes on Construction Jigs

• You do not have to use a jig to construct a structure.
• Jigs should be true. If you want to end with a level structure then your jig has to start level.
• Any errors in the construction of your jig will magnify during the construction of your structure because no one is a perfect builder.