If you want to hang a heavy chandelier from your drywall ceiling without a box or overhead joist, use an expandable toggle bolt that can hold up to 50 lbs. of weight per bolt. To do this, drill holes with specified diameter at exact locations, then insert bolts into these holes, making sure they have enough space between them and mark where they will go down into wall cavity after installation; Tighten nuts onto each bolt until they're snug against drywall surface; Attach hangers or brackets provided by the manufacturer onto bolts via screws (may require additional washers depending on hardware).