Casting is a kind of processes to make many number of same shape multiple times. Normally casts could be made from aluminum or steel. But steel is an old technique to be used for outdoor lighting products and much heavier. Thus aluminum casts are more suitable, as of weight and solidity against outside conditions. At the same time this preference refers to the person himself. It could be preferred in street lighting and garden lighting products than polyamide if the person himself like to use ancient stylish products as example.
Aluminum casts could be made in a simple techniques, starting by using two boxes. First one to be filled with soft sands and pressured - in hand maybe - in order to give it solidity as much as could be possible. Then to place the shape wanted on the other box and fill it with soft sand also, and pressure it then, and remove shape after it is pressured thus its stamp is left. Also to make a hole that be extended to the other surface of second box and then put both boxes over each other. Finally to get the aluminum filled in this hole flowing to make the shape inside boxes.
After all of these and waiting some time, boxes could be removed from each other and get the needed shape made from aluminum, then to modify it as to soften some angels somewhere or even cut unneeded extents out from cast. Finally to paint it if needed to be suitable for outside use.