A worldwide appeal to raise the £2.2m needed to start work on the new Snowdon café has been officially launched.
The deadline for raising the £2m is the end of June
The replacement for the building, once labelled "the highest slum in Wales" by Prince Charles, will cost £9m. The £2.2m shortfall must be raised by June.
A three-dimensional model of the designs is to go on display at the launch at Snowdon Mountain Railway's Llanberis station.
Appeal organisers say the new cafe will be "a building to be proud of".
Last month the two organisations officially combined their commitments to raising the shortfall by the June deadline.
Aneurin Phillips, chief executive of the park authority, said: "This will be a building for Wales to be proud of and its elegant and sustainable design will guarantee its iconic status.
"However, we now call for the support of people at home and abroad, and private donors or companies looking for a unique sponsorship opportunity, to help make this dream a reality."
President of the Snowdonia Society John Disley echoed Prince Charles' comments on the existing cafe.
"The present building is a disgrace to Snowdonia and Wales - it is a slum. I am always ashamed to take visitors from abroad to the summit - the site deserves the best.
"Wales now has the best stadium in the UK and concert hall - now our highest mountain needs a summit facility that we can be equally proud of," he said.
Robin Llywelyn, managing director of the Italianate village of Portmeirion and the grandson of the present cafe's designer, said: "The design for a new Snowdon Summit Building evokes Clough Williams-Ellis's original concept of a window on the world and interprets it in a contemporary style that reflects Wales's new found confidence in modern design."
The run-down current café is nearly 70 years old
So far, 75% of the total cost has been found but the whole project could fall through if the remainder is not raised.
Plans for a stone and glass building, designed to blend in with the landscape, were approved last year.
It would replace the existing concrete block housing the café and mountain railway station.
It is estimated that 350,000 visitors make the trek to the top of Wales' highest mountain every year by train or on foot.
In October, Welsh Environment Minister Carwyn Jones confirmed a £3m grant from the assembly government towards the project.
More than £1m has also been raised through grants from the Wales Tourist Board, Welsh Development Agency and Snowdon Mountain Railway.