Though 3D printers seem to come in many variations, most are actually very similar.
You typically have the RepRap Mendel or Prusa derivative with a boxy shape. Some printers may have a moving bed. Others may not, but generally they appear very much alike. However, three designs for filament 3D printing stand out as unique.
RepRap Prusa i3.
The latest version of the Prusa (shown above) looks like your typical printer, minus the decorative box. Click on through to see some designs that are quite different.