A method of rapidly producing a double-stranded target DNA is disclosed. The method includes the step of producing multiple single stranded primary DNA constructs having (a) partially overlapping and complementary internal regions that together define the target DNA, and (b) flanking regions on either side of the internal regions containing a PCR primer recognition site and a restriction enzyme recognition site. The primary DNA constructs are amplified to form a pool of double-stranded primary constructs, and a restriction enzyme is used to cleave off the flanking regions. The target double-stranded DNA is then assembled from the cleaved fragments. Hundreds of thousands of oligonucleotides can be synthesized and quickly and efficiently assembled into many different individual double-stranded DNA target sequences using this method.