A 'snackle box' is a tackle box (the compartmentalised plastic case used by fishermen for hooks and lures) repurposed to hold a variety of snacks — cheese, crackers, fruit, nuts, dips — for travel, picnics or screen-time munching. The 2022 TikTok trend gave the portmanteau wide recognition. If your teen makes one, they are following a wholesome organisation trend. Harmless and arguably healthier than crisps.