Sub for accommodating large devices

A sub, downhole tool, and method for manufacturing thereof, are disclosed. The sub may include one or more flow channels, each of which may be defined in part by a longitudinal groove formed along an exterior of a collar. One or more flow channel cover may be connected to the collar. The longitudinal grooves position the flow channels further outward to provide more volume within the collar that may be used for housing one or more devices. Upper and lower blind bores are fluidly coupled to the longitudinal grooves by angled through bores to complete the flow channels. A medial bore, which may be fluidly isolated from the flow channels, may be provided to house a device, such as an instrument, detector, or circuitry.