Watson and Crick «stood on the shoulders of giants» when they first described the three - dimensional, double helix structure of the DNA molecule in 1953. (teachermagazine.com.au)
The diffraction pattern you see not only suggested the likely double helix structure, but also that phosphate structures (what we now know as DNA bases) were on the outside. (io9.gizmodo.com)
This kit (pictured below) shows the three - dimensional double helix structure but, in my experience, is more difficult to use for modelling the processes of replication and transcription. (teachermagazine.com.au)