These enormous size transparent solids set are good for demonstration. This set consists of Cube (holes on two vertices to insert wire to show diagonal of 3D figures), Cu.boids, Cone (hole on top to insert wire to show difference between slant height and lateral 

Cube Dimensions approx. 10cm x 10cm x 10cm

Cuboid Dimensions approx. 10cm x 5cm x 15cm

Cone Dimensions approx. 21.5cm (Ht.) x 10cm (Dia.)

Cylinder Dimensions approx. 17.8cm (Ht.) x 10cm (Dia.)

Sphere Dimensions approx.  12.7cm (Dia)