This should not really be called a prop, but it is an "artifact".
We needed several inexpensive, practical (i.e. "working") gaslights to mount on the wall of the set. To keep the cost down, we needed to make them out of what materials were at hand; and for safety reasons, we wished to avoid dangling 110Volt power cords. To meet the second requirement turned out to be easy: I used 12Volt low-power garden lights.
The design here shows one or two features of gaslights, as I remember them:
This particular lamp suffered on its way back from the theatre, and the lamp base is no longer quite horizontal.
The baseplate, which mounts on the wall, is of two pieces of scrap 1" x 4" spruce, glued together, cut to shape and given an edge with a router. The plate is 14" tall.
The "gas-pipe" leading to the lamp is scrap 1/2" copper water pipe, painted black: it is 8" long.
The black base of the lamp is a plastic tub which came filled with Philadelphia Cream Cheese, and which was painted black.
The glass is actually a rose-bowl, purchased at the Dollar Store. I sprayed it several times with a coating that simulates an etched-glass effect.There is no hole in the bottom to pass wires through: the lamp bulbs are mounted in the base of the lamp, and shine through the bottom of the rose bowl. Much of the light gets transmitted by internal reflections within the glass, and illuminates the bowl due to the etching.
The two 12Volt bulbs fit into "nests" cut into a circle of wood that mounts in the bottom of the cream cheese tub and holds it rigid. The aluminum foil reflects stray light back onto the base of the rose-bowl.
With a spot trained on it to illuminate the area around it as well as its own internal light source, the "gas-light" looks quite authentic.