These trays are almost 300mm long, and so require a large format printer. The walls are 1.2mm thick, and so can be easily printed with 0.4mm or 0.6mm nozzles. A coarse layer height does not affect functionality. There is a small 45 degree chamfer where the outside surface meets the build place, this is to make sure that the insert fits well into the cardboard box; if you print with a brim, be aware of that feature when cleaning up the print.