The Portal Gun Pedestal is an entity added by PortalGun. When placed, it extends with a short animation. When it is fully extended, it can be right-clicked with a Portal Gun to place the Portal Gun onto it.
If a Redstone signal is applied, it will start spinning. If a Portal Gun is placed on the pedestal while it is spinning, it will will shoot a portal every time it faces N/W/S/E (sky directions).