This mould is made from thick semi-rigid ABS plastic.
Each Garden Stone you make will measure approx. 7½" x 6½" (19cm x 17cm) and they will be just under 1" (22mm) deep.
For those of you who would like to make concrete garden stones for houses with more than one dog, then you'll find a similar larger version here:
SPOILT ROTTEN DOGS LIVE HERE CONCRETE GARDEN MOLD