Cardboards rhymes with:
headboards, baseboards, billboard's, billboards, blackboards, checkerboards, chessboards, clapboards, dashboards, floorboards, headboards, keyboards, outboard's, outboards, pegboards, snowboards, surfboards, switchboards
headboards, baseboards, billboard's, billboards, blackboards, checkerboards, chessboards, clapboards, dashboards, floorboards, headboards, keyboards, outboard's, outboards, pegboards, snowboards, surfboards, switchboards