Yesterday, Joel Spivak and his fellow artists were screwing together misshapen plywood planks on Independence Mall. But by Sunday, those planks will be a gleaming art sculpture to honor Abraham Lincoln's 200th birthday.

And it will be covered in trash.

Spivak, 69, a South Philadelphia architect and a member of the Dumpster Divers of Philadelphia, heads the project.

"It will be a big, flat sculpture with a lot of holes in it, and we'll be able to attach a lot of stuff to it," he said.

At first, his models for the piece were angular and choppy. But he said that he decided it needed to be " more whimsical."

Spivak, a Philly native, said that when he was growing up "there wasn't a lot of material around, so you used everything."

He spent time with his grandfather, denailing boards and straightening them for reuse, he said.

He plans to leave blue recycling bins near the project for passersby to drop beverage containers - no glass, though - and to allow spectators to participate in the project.

"We'll let them do whatever they want," said Spivak, who has been involved since 1992 with the Dumpster Divers, an organization that declares: "Trash is just a failure of the imagination."

"I want to let [the piece] evolve," Spivak said. "You have to step back halfway through, and then come back in again."

As of yesterday, the Dumpster Divers had brought in 700 aluminum cans, 70 tubes of caulk, dozens of blue plastic lids and stacks of cardboard.

"Originally I wanted to make it look like Abe Lincoln's hat," he said, but he soon realized that it wouldn't be feasible.

Instead, "it's going to be freeform, like most of our art," he said.

Spivak also plans to have a portion of the sculpture devoted to letters to Lincoln.

The project is one of many parts of the Bicentennial Festival, celebrating the 200th anniversary of Lincoln's birth, Feb. 12, 1809.

The festival is based on the Great Central Fair of 1864, which was held in Philly's Logan Square and was the last event Lincoln attended in Pennsylvania before his assassination in 1865.