I enlarged 3 of the shapes that the students would not be able to make with their stencils and gave each group a set of these 3 nets to try out. When they were satisfied they had the correct answer, they glued the net under the correct heading on 1/2 piece of construction paper.
I have included the link to view this activity, Nets to Solids Card Sort. The card sort also comes with LARGE nets for students to fold if desired, and an Answer Key. My students used stencils this year, but, have used the large nets in the past.