DON'T use scrap wood. My very own brother did that -- plywood bits, painted wood scraps, even some particle board.

When the local fire chief (our cousin) found out he convinced the brother to toss EVERYTHING a thoroughly clean his smoker. Seems like the glues and the paints put off neat-o fumes like cyanide and sublimed lead and worse.

Ten pounds of crappie hit the trash...a tragedy, especially if you've ever wasted the time filleting crappie.