We have an electrical closet where network gear is also stored.   There are a few cisco small business switches and an opnsense device running on cwwk hardware.  A server rack takes up too much space, so this shelf was made to hold the devices.  Holes / slots were added to improve ventilation and reduce material / weight.  We used two regular drywall screws to attach the shelf within the closet.  There are no issues holding the weight of the 3 devices and 22 cat cables also connected to them.  The print is a little long, but wanted quality and strength.

The print profile has custom layer infill around the screw recess holes for added strength.