3d printing and laser cutting/engraving are two different things. 3d printing is generally squeezing out a thin filament of molten plastic in the shape you desire. It starts with nothing and builds onto that to make your piece. A laser cutter is only removing material. If you want a 3d rendering, you can either cut "slices" like layers and glue them together, or you can cut out "walls" and glue them together to form your structure. You would engrave a picture. It can be done but you cannot expect it to look good without the right picture and the right alterations to the picture using photoshop or photograv or some software like that. Maybe you should do a little googling and spend some time on youtube. There are lots of good example videos of both technologies there.