You can model almost anything that is composed of thin "wires" using a lattice, with relative ease.
1. First, draw a grayscale image of what you would like from the front in a painting program. In this case, I was making a gate for a graveyard image. Make sure your image is a square, preferably one of the standard lattice sizes (256x256, 512x512, etc) so there will be no skewing. If you need the wires to be round, then blur the image ahead of time in your image editor a few times. Smoothing it in Bryce doesn't always work the way you want it to. (the outline is just to accentuate the square.)
2. Once you have drawn your gate, all you have to do is copy it and paste it into Bryce. To so this , click on the Pictures tab in the elevation editor and click Paste on both boxes. Make sure the bottom clipping bracket is moved up a little to get rid of the ground (it should be by default.)
3. Exit the terrain editor and enter the attributes dialogue for your lattice. Change the Y size value to whatever thickness you want the lattice to be, apply a material, and you're done!