Build Madison is playing host to its fourth annual “create-a-thon” Saturday and Sunday at Sector67, the organization announced. The event is free to attend.

Like the other hackathons in Madison, Build Madison is seeking designers, developers and the like to collaboratively create a project in 24 hours. Idea pitches begin at 2 p.m. Saturday, and presentations, which are open to the public, are made at noon Sunday.

Last year, more than 70 people participated and $850 in prizes were awarded.