The time required to make and test prototypes can be compressed by days, or even weeks, it's claimed, when using the MicroPen precision direct writing system, which also eliminates the cost of hard tooling. With the system, circuits are easily designed- with as many layers of conductors, resistors, and dielectric as needed- using its AutoCAD station. The system then directly writes the circuit, in thick-film inks, on a ceramic substrate. There is no need for photo tools or screens and users can create a series of prototypes while they're debugging, making variations in selected parameters from one to the next. Users simply fire all the prototypes as a batch and then test them as a group, thus saving weeks of development time while eliminating the cost of hard tooling.Production parts can then be made using the same system. All parts will be identical to the prototype because they're made by the same process. Line widths can be as small as 3 mils, with spacing that's even closer. And there's no practical limit to line thickness because multiple passes of the pen can be made with no need for firing in between. The written line is measurably more uniform in cross-section than a screen-printed conductor, which reportedly improves the precision of the circuit.