A method of plugging a filter, comprising: positioning a mask layer over the filter comprising a plurality of intersecting walls, wherein the intersecting walls define at least one channel between the intersecting walls; perforating the mask layer proximate the channel to form a hole, wherein the hole extends around a portion of a perimeter of the channel such that the mask layer defines a flap extending over a center of the channel; passing a plugging mixture into the channel through the hole in the mask layer; and sintering the plugging mixture to form a plug within the channel.