Hi Joe,
I purchased a 2"x2-1/2" x3/4" glass block, as a gift for my wife. In the middle of the glass is a single 3 dimensional, long stem, rose with the words "I love you" printed underneath the stem. It is visible from all sides. When turned 90 degrees the rose looks like a rose and the printing is just a straight line. I was told , by the salesperson, that it was done with two lasers. When the beams intersected they created enough heat to melt the glass on the inside of the block, thus making the design. They had all sorts of designs, dolphins, dogs, cats, flowers, churches, etc. they are really quite nice. You can probably find them in any store that sells tourist items. I don't remember who made them and I can't find the box it came in. Granted this would require a pretty sophisciated setup to do, but what you are asking is being done by someone :-)
Daymon