For several years there have been many efforts to employ ink jet technologies in the fabrication of consumer electronics. The potential of displacing large and expensive pieces of electronic fabrication equipment and processes with seemingly appropriately scaled inexpensive alternatives is attractive. However, of course, the devil is in the details. Feature size, accuracy, registration and materials all have severe impacts on design rules, processing, performance and the types of devices appropriate to the technology. In this article, we describe aspects of the jet-printing technology for large-are electronic device processing that have been developed at PARC. These aspects include fine feature patterning, multi-layer registration for thin-film transistor device fabrication, printing of solution processable semiconductor and conductive materials, and printer color filters. The focus of this work is to demonstrate the wide range of applications for jet printing in the area of device processing.. Examples of working proto types of displays, imagers and microfluidic devices produced through ink jet printing are given and we discuss the tools used to design these devices.