a canister including an elongated hollow plastic body having a wall with inner and outer surfaces , an edge portion on the wall defining an open end , an end on the edge portion extending transversely to the inner and outer surfaces , a porous plastic member having an outer edge portion extending across the open end and fused to the end , an inner portion on the porous plastic member located radially inwardly of the outer edge portion and extending into the body and fused to the inner surface of the wall adjacent the end thereof , and a gas - treating material in the body . a method of fabricating the above canister including the steps of applying pressure and vibratory welding energy to the porous member to thereby cause the member which was originally planar in shape to have its outer edge compressed against the end of the body and fused thereto and the central portion inwardly of the outer edge forced into the body and its outer edge fused to the inner surface of the body adjacent the end .