[mhss1992]

Using a few linear constructs on the Editor, it's possible to get many kinds of symmetry. For example, to get a simple bilateral symmetry, create a new construct and flip it horizontally, making it a mirror of the static original construct (I think this menu is only available in the editors of Apo 2.05 and 2.08, 2.02 doesn't have it. I use 2.08).
Other than that, go to Options, Random, choose a symmetry pattern in the Forced Symmetry menu, and create a new random batch. Then, just go to the editor and look at the constructs with a linear variation of 1, near the center. You can learn how to do symmetry with that.

EDIT: in case you're curious, to create this perspective I used in Tunnel, just create a linear construct, and then another one, a bit smaller, in the same place.