6 years old
Here is an unusual twist for fun. Have a blown up, life-size cardboard photo of your favourite Potter actor or character for guests to have their photos taken with. Cost is involved in arranging the cut-out as well as for a photographer, and a fee is usually charged for people wishing to purchase their photo with the cutout.
Popular life-size photo cutouts of Harry Potter, Dobby, etc. are a fun way for people to have their photo taken with Harry without him actually being there.