This flyswatter consists of two parts that can not be loaded together into the slicer. The flyswatter is to be sliced with an appropriate value for INFILL and without any TOP/BOTTOM-layer. The handle can be sliced with default-settings. See screenshots.
You have to choose an INFILL that produces a full grid for each layer.
In Cura (for example) 22% is suitable - 25% is not.
Inspired by this thing.