A filter medium is embossed to form embossments and the filter medium is then cut at least in some sections by a cutting device such as a water jet, a laser beam, an ultrasonic cutting device, or a cutter, by moving a point of impact of the cutting device relative to the filter medium to produce a cutting line. After cutting, the filter medium is folded. Alternatively, the filter medium is folded to folds and then at least some of the folds are pulled apart at least partially. In a region of the folds which have been pulled apart, the filter medium is cut at least in some sections thereof by the cutting device by moving a point of impact of the cutting device relative to the filter medium to produce a cutting line. After cutting, the folds are reset.

A muntin bar fabrication system can be used to efficiency produce a wide variety of different types of muntin bars, allowing the fabrication of both standard and custom muntin bar assemblies for doors, windows, and other fenestration products. In some examples, the fabrication system includes a muntin bar stock storage assembly that holds multiple different types of muntin bar stock. The system also includes a muntin bar stock extraction device that extracts one of the different types of muntin bar stock from the storage assembly and conveys the extracted muntin bar stock to a feed device. The feed device feeds the extracted piece of muntin bar stock into a cutting system that includes a multi-axis cutter. The cutting system that performs one or more cutting operations on the extracted muntin bar stock so as to fabricate one or more individual muntin bars from the extracted muntin bar stock.