This is the biggest box you can print on a BambuLab P1P. No supports required, simply use 60mm pieces of filament as hinges to join the 4 walls to the bottom.

Inner space: 212 x 212 x 212 mm (8.6" x 8.6" x 8.6").

Inspired from this great design: https://makerworld.com/en/models/72189#profileId-76352

Completely unrelated: The Vertical Decor Collection:

• Slender Striped Vase: https://makerworld.com/en/models/91147#profileId-97491
• Fat Striped Vase: https://makerworld.com/en/models/91133#profileId-97479
• Candleholder Tall: https://makerworld.com/en/models/91168#profileId-97509
• Candleholder Short: https://makerworld.com/en/models/91158#profileId-97497
• Candleholder Double: https://makerworld.com/en/models/91181#profileId-97517
• Tissue Box Holder with Bottom Lid (Scotties): https://makerworld.com/en/models/73097#profileId-77641
• Tissue Box Holder without Bottom Lid (Scotties): https://makerworld.com/en/models/73057#profileId-77633
• Tissue Box Holder without Bottom Lid (Kirkland): https://makerworld.com/en/models/67057#profileId-70913
• Weightless Spheres: https://makerworld.com/en/models/99069#profileId-105629
• Weightless Teardrop Vase: https://makerworld.com/en/models/106259#profileId-113422
• Downhill Skier Skier Door Frame Topper: https://makerworld.com/en/models/106214#profileId-113390
• Tail-grabbing Skier Door Frame Topper: https://makerworld.com/en/models/126631#profileId-136909

Also:

• Ringosaurus bigger and deeper: https://makerworld.com/en/models/57828#profileId-59525
• Unlocked Level Cake Topper: https://makerworld.com/en/models/104796#profileId-111855
• Biggest Gift Box: https://makerworld.com/en/models/84040#profileId-89836
• Large Copter Propeller: https://makerworld.com/en/models/64664#profileId-67877