How do I make a block texture different on all sides? (1.19.2)

I am trying to make a texture for a custom generator block that is similar to a furnace. At first, I copied the model for the furnace, and was able to change the top and front with ease. However, I want the bottom to be different from the top and the back to be different than the sides. I tried simply adding a line for the back, but it still rendered with the texture of the side. I then tried adding a texture for each side ("left", "right", "bottom", "back"), and now the only two sides that render are the front and top. Any help appreciated.