Lay out drop sheet or newspaper and place letterbox on top. Using primer, paint all surfaces of the letterbox (inside and out). Let dry.
With chosen tiles in mind, think about or sketch on paper a design that you’d like to create on each face of your letterbox. Also think about whether you’d like to tile your house number on the front face of the letterbox.
Try lightly sketching your design onto the letterbox.
Wearing heavy-duty gloves and eye protection, break tiles to desired size using tile nippers. Or, gently tap tiles using hammer on a sturdy outdoor surface. For safety, and so you don’t mark tiles, cover tiles in a rag to prevent shattering.
Following pack instructions, use tile adhesive to stick main parts of your design onto your letterbox (for example: a sun, birds, flowers, house numbers, etc). Apply a small amount of adhesive to back of tiles using blunt knife and press in place.
Fill gaps between your main design using more broken tiles. You may wish to fade background colours, use random colours, or a single background colour. Stick tiles in place using tile adhesive, leaving small gaps in-between, and wriggle each a little so pieces will sit flush with surrounding tiles.
Continue sticking down tiles until all surfaces are covered. Try using mosaic tiles for narrow edges of the roof, along the top ridge, and around the base of the letterbox. Remove excess adhesive using knife where necessary and let dry.
Prepare grout following pack instructions. Force grout into all gaps using knife. Remove excess grout, where necessary, using knife. Leave to part-dry (usually 10-15 minutes).
Wearing rubber gloves and using a dampened sponge, wipe away excess grout from the face of tiles. Do not remove grout from gaps. Fill a bucket with fresh water and use to rinse the sponge. Wipe away all excess grout. Let dry. Polish surfaces using a dry cloth. If using a post, repeat steps to decorate.