Mia- I think this envelope Design is very gorgeous，the colour use make it look like very superior. from this design, I know that colour use is very important, it can created different visual communication. this image just show the back of the envelope, it has a logo that stamp on the envelope, it is a very good idea that can be reference, besides, the envelope's back just covered half of cards, I think it is easier to insert cards.
Free camera gift box template - from Papercraft Inspirations magazine (This would make the perfect Silhouette cut file). http://www.papercraftinspirationsmagazine.co.uk/category/blog/free-camera-gift-box-template.htm