Those of us undertaking the PacificMeister build have to contend with the tiny gap between the motor and the very slightly larger outer tube housing into which the motor slides. These walls need to touch to keep the motor running as cool as possible. Rather than relying solely on heat paste to fill this gap I have found that the metal from a Miller Lite beer bottle fits just about perfectly. Be super careful cutting the bottle as the metal is extremely sharp. I may still use a thin coating of heat paste to ensure a really tight fit.