There is about a 7mm (1/4 inch) gap between the mount and the back of the case and open on the sides and top. The right-side (left-side if viewing from the rear) is where the fan is, and that side has more of the vents completely un-obstructed. I haven't noticed the scope getting any warmer than when it was sitting on my desk. I was planning on iteratively cutting out holes/shapes in the design for ventilation while testing for strength, but this seems to work fine so I didn't feel like making more iterations and creating more filament waste.