A film studio complex earmarked for Straiton will cost more than £230 million and take at least five years to complete, backers have admitted.
The price tag of the Pentland Studios, which would be built next to an existing retail park, has risen by more than £80m in less than a year.
A host of new uses are being put forward for the project, which has already been three years in the planning stages, but has yet to win official endorsement from the Scottish Government.
And it could be another two years before any film or television productions are able to use the facilities at the 106-acre site.
New details of the £232m development, which has been opposed by Midlothian Council chiefs, have been released to industry representatives.
The complex is now being touted for Edinburgh Festival performances, a rehearsal space for performing arts companies such as Scottish Opera and the Royal Scottish National Orchestra and a hub for computer games development.
The studio consortium has mounted an appeal to the government over the handling of the project by Midlothian Council. Ministers are being asked to rule on the project after the authority raised concerns it would cause unacceptable disruption to local residents, threaten the expansion of nearby developments and blight the landscape.
New details of the Pentland Studios scheme have been announced weeks after the government threw its weight behind plans for a permanent studio in Cumbernauld.