These tealight holders are made of solid mahogany, however I think that they could also be made of thick furniture grade plywood. They could be finished natural/clear, or they could be finished with colored stains. I also think that there are good combinations between various woods and metals; for example: oak and brass are a combination, maple and aluminum are a combination, and the mahogany and copper that I made these holders out of. If colored wood finishes are used, a whole palate of combinations are possible with anodized aluminum inserts. And, of course, various sizes can be made as well - lots of color, material, and size combinations are possible.
There are only nine cuts to be made once the square block blank is made. I made the square blanks out of a large piece of mahogany , then I just put the beveled edges on via an angle bit mounted in the router in the router table, and used a forsner bit in my drill press to make the recess hole for the copper cup - which is simply press fit into the hole. The finish is simply tung oil.