In this tutorial, we focused on constructing a DNA molecule with a double helix structure using Avogadro v2’s Builder DNA tool. The video covers: Selecting and adding individual nucleotide bases to build the DNA sequence. Automatic base pairing: The builder automatically pairs complementary nucleotide bases (A–T and C–G) between the two strands, ensuring correct hydrogen bonding and sequence complementarity. Helix formation: Once the bases are paired, the builder arranges the two strands into the characteristic right-handed double helix, generating the proper twisting and spatial orientation of the backbone. This tutorial is ideal for students and researchers in biochemistry, molecular biology, and computational chemistry interested in DNA modeling and 3D molecular visualization.