Since the inside of most prints is hollow with an infill grid, putting an outer layer, especially on the top of the print, can in some cases produce some gaps where this shell layer covers these hollow areas. If this is the case, the gcode is not adequate for what you need to print and modifications must be made in CraftWare after clicking on the “Slice” option. Under the “Basic” tab (the first visual to pop up most often right after clicking) you will find a section with the title “top/bottom shell” and you can adjust the thickness of the top layer here by increasing the layer number. If you need some extra insurance, or in the case that the infill is far below that needed to support a successful print, you can also modify this amount in the infill section located right below the top/bottom shell one.
