Screw Caps Alternative ways to recycle Recycling Cart Metal screw caps should be removed from the glass bottle and recycled loose. Plastic screw caps from plastic bottles should be placed back on the bottle for recycling. Plastic Caps Are Different Plastic caps have separate disposal instructions. Find out how to dispose of plastic caps. Recycle Metal Jar Lids Metal jar lids greater than 2-3 inches in diameter can be recycled. Make sure they are separated from their jars so they can be sorted correctly. Alternative Ways to Recycle Metal Screwcaps Are Scrap Metal Metal screw caps can be collected and recycled with other scrap metal. Simply separate aluminum caps (non-magnetic) from steel caps (magnetic).