The OWL printers use a rather complex lensing system to reduce their laser footprint. After watching someone's beta assembly video, it looks like there's plenty of room in front of the Peachy's laser for a small lens stack. Just making a smaller aperture would not necessarily make the beam tighter, as you start getting dispersive lensing effects at very small apertures for physics reasons that I can't remember the names of.

Of course, that would be something for an upgraded or modded Peachy.