On Saturdays (from 7 July to 11 August) there´s direct bus link from Helsinki.
Departure from Helsinki, Kiasma museum bus stop 10:30 am. Departure back from Fiskars at 4:00 pm.
Tour price 30 € /adult, 10 €/child 4-17 years, 20 € senior citizens and students. Booking and more information: www.frimantravel.fi