Your local UPS Store or U-Haul location typically sells oversized wardrobe or mirror boxes, which offer some of the largest flat surface areas available for purchase. Where to Find Large Cardboard for Free
Buying new ensures the cardboard is clean, structurally sound, and available in specific dimensions. where to buy large pieces of cardboard
If appearance is less important than size, many businesses are happy to give away their waste to save on recycling costs. Your local UPS Store or U-Haul location typically