A new chapter in Methods Mol. Biol. (Currin et al, 2017. Vol 1472, 63-78) describes our SpeedyGenes method that allows the assembly of DNA sequences with fewer errors and its use to encode extensive, statistically designed sequence variation at any position in the sequence to generate diverse yet accurate variant libraries. We also describe the integrated use of GeneGenie to design DNA and oligonucleotide sequences, followed by the procedure for assembling these accurately and efficiently using SpeedyGenes. These methods provide useful tools for synthetic biology and biotechnology where gene synthesis is utilised to assemble any desired DNA sequence, which can then be incorporated into novel parts and pathways.