This activity allows students the opportunity to design their own models of DNA. I open up my craft supplies and allow students to decide what should be used to represent each part of a nucleotide. They then build it, draw it, and explain it to the teacher, as well as answer some basic questions about DNA and structure. They have to explain and show a gene segment, and it needs to be in the shape of a double helix.
I made this activity when I couldn't find anything that allowed for student exploration and ownership. It does not tell them exactly what to use, only the parts they need to include. It's not fancy, but it's editable. :)