More to explore:
3D Box Card Tutorial - Stunning card, and not that hard with these instructions!
How to make a 3D card in a box - part 3 - YouTube
How to make a 3D card in a box - part 1
DIY Simple 3D Gift Card
▶ Card in a Box Tutorial - YouTube
Card in a Box by frenchiestamps.com - she converted size to fit in a regular envelope
Wow! This card is just awesome with the cupcake. I haven't seen one like this before!
Baby Crib Card In A Box 3D SVG by MyCasualWhimsy on Etsy, $1.99
Fun winter card!
3D Birthday Card Box Card with Balloons by APaperParadise on Etsy, $8.50
Love this!!! Too cute!!
Gorgeous Blush in Shabby Chic 3D box card - tutorial