Some embodiments include a method in which a mixture of polynucleotide structures comprises a set of surface shapes. Surface shapes of some polynucleotide structures are complementary to surface shapes of other polynucleotide structures. The complementary surface shapes lock together along interfaces between adjacent polynucleotide structures to incorporate the polynucleotide structures into a polynucleotide mask. The polynucleotide mask is used during fabrication of features associated with a semiconductor substrate. Some embodiments include a method in which a semiconductor substrate comprises registration regions configured to adhere individual polynucleotide structures to specific locations of the semiconductor substrate. The adhered polynucleotide structures are incorporated into a polynucleotide mask which is used during fabrication of features associated with the semiconductor substrate.