The present invention describes electroformed thin-wall nickel core drills that are impregnated with diamond abrasives. The thin-wall core drills are formed with a plurality of raised portions and an equal plurality of recessed portions, with each raised portion alternating with a recessed portion, the raised and recessed portions are substantially parallel and are connected by transition portions. In another embodiment, some of the transition regions are formed with intermediate steps or partially raised and recessed portions. These intermediate steps or partially raised or recessed portions allow more uniform distribution of matrix material across a kerf width D1 as the core drill is spun, thereby, giving the cut edge a substantially square profile.