Abstract: Devices and methods for counting planar substrates stacked on a first plane are disclosed. Image capturing sensors are arranged collinearly in a manner substantially perpendicular to the first plane. The image capturing sensors are configured to capture images of portions of counting sides of the stacked planar substrates. The image capturing sensors are configured so that the images captured by every two consecutive image capturing sensors comprise an overlapping portion of the stacked planar substrates.

Abstract: 3D printing material blends (110) are disclosed configured to be used in a 3D printer. The 3D printing material blends comprise a 3D printing material portion and a magnetic nanoparticle portion (S1, S2, S3, S4). The magnetic nanoparticle portion is embedded in the 3D printing material portion in such a way that the 3D printing material blend is encoded with a uniquely identifiable predetermined code. Furthermore, 3D printing units and systems having sensors for identifying 3D printing material blends and methods of encoding 3D printing material blends are also disclosed.