Vaseline and caulk to make small molds. For reproducing small details, coat the original with Vaseline, then cover it with a thick layer of 100 percent silicone sealant. Let it cure, remove the mold, and fill with plaster of paris.
Making a Beautiful Impression Rachel Dein's method of plaster casting captures flowers and foliage in a unique and delicate way. She creates her original casts by making an impression in wet clay and then pouring plaster directly over it.