When it comes to making money with a laser cutter there are two main methods; service provider and manufacturer. A service provider would provide laser cutting services to others who need laser-cut parts, while a manufacturer would focus on producing their own part for selling.
In order to provide laser cutting services, it is essential that customers have a wide range of material options as only focusing on a few materials will severely affect access to customers. However, stocking multiple materials may require multiple laser cutting machines as different laser technologies are good for different materials. For example, CO2 lasers are great for cutting leather and cardboard, but fiber lasers are more appropriate when cutting harder materials such as steel.
Being your own manufacturer means that you design a laser-cut product that you produce in mass and ship. As such, there is no requirement to stock a wide range of materials which significantly reduces the complexity of the setup (i.e., only one storage bin for material, and no need to check designs before they are manufactured). Such parts that could be produced include keyrings, picture frames, wooden coasters, and decorative cards. This business model, however, requires a marketplace to sell items that can prove to be challenging when competing with other manufacturers.