Diy Waterproof Outdoor Storage Box . Then predrill, countersink and screw the frame together with long screws. Apply construction adhesive to the slats, and then center the lid on the slats. Large 300L Garden Storage Outdoor Box Waterproof Plastic Utility Chest from www.ebay.co.uk Christopher knight home santa rosa wicker storage box. This box has a relatively compact footprint, measuring just 57.8 x 44cm. It is important to keep the wood wet with varnish for 10 minutes.