Custom Shipping Boxes - Custom Printed Mailer Packaging Boxes made in any sizes, shapes, and design. PYB offer quality packaging services with free shipping. Custom Mailer Boxes wholesale has been around for quite some time now. Every fashion plate that moves to the runway will have their very own custom printed box. Every major event that takes place will feature a box of some sort. The box is the backdrop to the entire event and is an important part of what is taking place. In addition to being the backdrop, the custom printed masiler box plays a key role as well as having a significant role in the success of the whole event.