This model is a customized version of the Pi 4 Snapfit 60mm fan case from @ash.
I just wanted to have the cool infill look also on a case for the Raspberry Pi3, so I adjusted the holes for the plugs. There is also a 60mm and a 40mm fan variant of the top.
Also make sure the set the top and bottom layer to 0 and a 2D infill in the slicer to get the look-through look.
Note to the picture: Seems that I have a taller fan, so the edge of it lays directly on the USB ports, so its pushing a little up and causing the visible gap. Nevertheless the case keeps closed.
The author remixed this model.