Channels is the a tool to quickly display the strcture of the channels inside a hydraulic block.
To check the structures of the channels you have created during the modeling process you just have to click a button and Manifold Designer begin to study the block to understand the REAL internal structure and display the channels it has found.
To allow this complex calculation it's enough to identify what we call "Main hole" and give it a name and a color. Manifold Designer will follow the path of the channel starting from this "Main Hole" up to the end of channel.
To allow for a better visualization of the channels you can move them out of the block. This way you will be sure to see all minimum detail.