Making a stable DNA model requires some form of support that both suspends the model upright and prevents it from losing DNA's characteristic helical shape. The easiest method is to suspend the model between two foam blocks supported by dowel rods. The dowel rods will support the upper foam block, suspending the model and preventing it from untwisting. Purchase both the foam blocks and the dowel rods at your local craft store.
Build your DNA model using any desired components. Models built out of paper clips assemble quickly but may not be visually impressive if you need it to stand out next to a science fair display board. Models built out of beads and candy stand out but are difficult to manipulate.
Lay the model flat on the work surface as you work.
Include some form of pointed support at the end of either leg of the DNA backbone. For example, if you connected your DNA components with toothpicks, add an additional toothpick to the end of phosphates or sugars. You can also use partially unwound paper clips or pipe cleaners.
Measure the length of the DNA model.
Cut two dowel rods to the same length as the DNA model. Use thin dowel rods and you can cut them with a utility knife.
Select two square, foam blocks wider than your model.
Lay one foam block at either end of the DNA model.
Press the bottom supports that you created in Step 3 into the centre of the foam block. Make certain the model is stretched to its full width.
Repeat Steps 7 and 8 for the other end of the model.
Enlist the aid of a friend to complete the assembly.
Hold both blocks and lift the DNA model until it is upright. Rest the bottom block on your work surface. Have your helper lift the centre of the model to ensure that it does not come apart.
Hold the base of the model stable while your helper twists the upper block to create the characteristic helical shape. Twist the upper block so that the position of the corners matches. Do not release the base.
Press one of the dowel rods into a corner of the bottom base and then press it into the upper foam block.
Press the other dowel rod into the base at the corner diagonal from the corner in the previous step. Then press it into the upper block.