Why would a person want to use this power to make a person? We already have reliable and enjoyable methods for person creation, which has resulted in people being widely available in many locations. If you wanted a person for something, synthesizing a pile of $100 bills makes a lot more sense.

Clearly the smart play is to synthesize yourself a t-rex. If you find it difficult to rustle up enough carbon, go buy some charcoal and light a fire.