If you are cutting out channels, you are sort of negating the contribution of the core as you will be cutting through the outer skins, so you will lose the rigidity from the core. You may be better off making it as a monolithic laminate.

Hello, I need some advice on making a 16mm thick block of carbon fiber. I know a core material should be used, however I'm unsure of which is best for my application. The block will be approximately 20cm square 16mm deep. The block will then need channel's cutting out. It is going to be used as a bracket between a motorbike engine and radiator. The radiator and engine weight are approximately 50kg so I need something to be able to hold this weight under force and vibration, the temperature exposure will be minimal. 30-50deg. I'm thinking lantor soric sf 3mm with a 450g carbon between each layer and on the outer surfaces for resin infusion. Any honeycomb structure would add far too much weight from resin.