feed the seam of a wool cap

[IQU3838]

Hi,

Could anyone help me out with the underlined part?
Thank you very much.

"A man stands there in Carhartt coveralls, feeding the seam of a black wool cap through his hands. He reeks of smoke."

Thank you.

 

[5jj]

If you feed something through your hands/fingers, you pass it through.
The seam is the thicker part where two edges have been sewn together.

He is doing with his cap what some people do with rosaries or worry-beads.