These are some t-shirt designs I did for NewSong a couple of Easters ago. The second one was a bit more clever in it's use of the letters, but they opted for the first one which is visually more of an immediate read. Being the geek that I am, I actually looked up the bond angle for the water molecule which, in case you don't want to hit the link, is 104.5 degrees.
As anyone who has made ice before knows, water expands as it freezes. The reason for this (as the article explains) is that the organized lattice structure of its solid form creates "space" through the weaker hydrogen bonds that occur between the H2O molecules. In liquid form, the v-shaped units mingle and tangle up a lot closer to each other. It's somewhat analogous to a steel bridge with those X-shaped or V-shaped supports versus just a random pile of those same girders.
So, you may ask, "Why do you bring this up Mr. Chemistry/Engineering Geek?" (Actually, I was never too keen on Chem and never studied Engineering.) I just thought they are good reminders for me to embrace more structure in my life, a constant uphill struggle for as long as I recall. Like many artists and slobs, I tend to view structure as being restricting and confining.
However, if you imagine a girder bridge, it's obvious that one with those X's and V's organized into a structure allows space to go through it, poke your head out crossing it and climb it. Now, if those girders were not so organized, not only would the bridge be more difficult to navigate, but I wouldn't have much confidence in the strength of the bridge to hold up under the strain of any additional weight.