Between 200 - 600 prim count. But if you want all the building hints and details, they are pinned to the Opensimfest Discord channel
https://discord.gg/8QMqVpr5KW (top left, a little pin icon)
To be a builder at OpensimFest, follow these simple steps:
1. Register for a free 'ticket' on
https://www.opensimfest.com/register
2. Sign up to Discord and join the Opensimfest channel
https://discord.gg/8QMqVpr5KW
3. Start thinking up your Medieval/fantasy themed build to promote your region, project, grid, or art, and begin building your exhibit on your home grid
4. When grid account registrations goes live, you will be able to make a local avatar and use that to bring your build to the Festival (A local avie will make life easier for the organizational part of the Fest.)
5. When the grid opens to builders, get your assigned parcel and put up your exhibit.
6. Be there to enjoy the 17 days of events, parties, music and visiting all the exhibits and merchants!
After the grid goes live, you will also be able to ask for specific advice regarding your build's lag potential, but please read the FAQs first, to avoid disappointment.