I wanted the ability to connect a monitor, keyboard and mouse to my Voron's Pi without having to take the bottom panel off.
The opening is sized for this BATGE HDMI extension, from Amazon:
and this URWOOW dual USB extension cable, also from Amazon:
Any SMA male or female wifi antenna extension connector should fit through the ¼" hole.
The author remixed this model.
Added install points for USB and HDMI Cables, and a Wifi Antenna.