The attached is a 3D model of a DZ-2500C switch machine cover with a dwarf signal attached. The 2500C is represented by the magenta box. The slot allows finger control of the 2500C switch button.
The signal rides above the Red and Green LEDs in the DZ-2500C so that two fiber-optics cables can be run from the LEDs to the signal head. The signal head lamp, not shown , will light red or green depending on which LED is lit and coming thru the FO cables.
The signal is 360 degrees rotatable on the cover to point in whatever direction is required.