Custom Flat Cardboard Boxes

Choosing a Style for Your Flat Cardboard Boxes

A roll end tuck front mailer is the most popular style. It folds from one piece, has double-thickness side walls and closes with a tuck flap that locks under dust flaps, so it needs no tape for light contents. A crash-lock tray with a separate lid suits presentation pieces, where the customer lifts the lid off rather than opening a hinge. A tear-strip mailer with a peel-and-seal strip suits high-volume dispatch because packing is a matter of folding, peeling and pressing.

For prints and diplomas, we can add a scored backing card or corner pockets inside so the item cannot slide and rub against the walls. For clothing, a sheet of tissue folded over the garment does the same job and makes the opening feel finished.

Measuring Flat Items Properly

Lay the item flat and measure the length and width at the widest points, then measure the thickest point, including any packaging such as a cello sleeve or a rigid backing board. For prints, add 5 to 10 mm on each side so the paper does not touch the walls, and add the thickness of any backing you plan to use, as the guide to measuring your product explains. For folded clothes, fold the garment the way you will pack it, press it lightly and measure the result, not the shop-display fold.

If you sell several sizes, such as A4, A3 and square prints, it is worth asking whether one or two box sizes can cover them with a backing card. Fewer sizes keep stock simple and setup costs lower, and an insert costs less than an extra box design.

Books deserve a special mention. A wraparound book mailer folds tightly around the cover, so a paperback or hardback cannot shift and bump its corners. It is sized to the book's height, width and spine depth, and suits publishers and bookshops sending one or two titles at a time.

Printing Inside and Out

Plain kraft boxes with a one-colour logo on the lid are practical and cost-effective. For a stronger first impression, full-colour printing on a white-lined board lets you cover the outside in pattern or photography. Printing on the inside is popular with artists and small fashion brands, because the customer sees it the moment they open the lid, and the outside can stay understated in the post.

Keep the address area clear. A courier label needs a flat, light-coloured space of about 100 x 150 mm, and a busy pattern underneath can stop scanners reading the barcode. We can leave a printed panel blank for exactly this purpose.

• Outside lid: logo and a clear label area
• Inside lid: thank-you message, care notes or social handles
• Side walls: a short brand line visible when stacked
• Tuck flap: a neat place for a discount code

Who Uses Flat Mailers

Illustrators and photographers sending prints, publishers sending signed books and calendars, schools and awarding bodies sending diplomas, fashion labels sending folded T-shirts and scarves, and stationery makers posting planners all rely on the flat format. So do businesses posting marketing kits to clients, where a slim branded box looks far more considered than a padded envelope, and art sellers who want the deeper art print shipping boxes for mounted work.

For any of them, the box also becomes part of the product. Customers keep good flat boxes for storing their own papers and photographs, which keeps your logo in their home long after the delivery.

Flat boxes also suit businesses that send paperwork with weight to it, such as framed diplomas, laminated menus or sample swatch books. In those cases we lean toward B-flute board so the box resists bending when it is squeezed between parcels in a sack.

Decide Letterbox or Parcel First, Then Measure the Thickest Item

The one decision that shapes a flat box is whether it must go through a letterbox. If it does, the outside has to stay within 25 mm deep, 250 mm wide and 353 mm long, so we work from those limits inwards and the board thickness comes off the inside. If it does not, the box can be deeper and the choice opens up to B-flute for heavier contents. Then measure the thickest thing you post, with its sleeve or backing board. Keep a plain 100 x 150 mm panel on the lid for the address label.

Send the item measurements, a rough monthly quantity and whether letterbox sizing matters, and a custom quote comes by email within one working day, minimums low and quoted per job so a new print shop can start small. A free design proof shows the dieline with inside and outside print. Production takes 4 to 7 working days after approval and the flat bundles travel on free tracked delivery to UK mainland addresses in 2 to 3 working days. Sellers who post folded clothing alongside prints usually add the slim shirt boxes in the same style.