A model railway in Leicestershire suffered £6,000 damage when vandals attacked the site.
The North West Leicestershire Society of Model Engineers on Hermitage Road, Whitwick, was targeted sometime between 17 and 20 June.
A building at the centre of the outdoor replica railway had been broken into and CCTV monitors smashed.
Officers said they were optimistic about finding witnesses who may have information on the attack.
Pc Rich Dudley, said: "The society is a non-profit organisation, which makes something like this particularly sad and upsetting for the members.
"People in the area will be upset to hear about the damage and we hope that everyone will help us as much as they can to find out who is responsible.
"The damage happened at some point over three days so there's a good window of opportunity for witnesses to have seen what happened."