Great effect as the mint box is such a familiar item (for US audiences) so is nicely surprising.
Stick another tin with some small metal nuts in it to create the illusion of disappearing mints.
Only complaint is the lack of spares already spoken of in other reviews. I sadly stored my tin
for a few weeks with the gimmick in the "armed" position, effectively introducing a bend in it
making it ineffective. I removed it and have managed to get it back to working order but have also
since purchased materials to make replacements. The critical find was the right metallised film:
Grafix Metallized Dura-Lar