Hello, As I have visited the reference link and it is basically design and choose your own frame type.
There is choice of the pictures and can customize on the checkout like in five steps.
Frame, Matt, Glass, Cropping, Wall color.
This allow to choose the size of the frame too.
I got the over all idea, i would like to discuss more on this.
Currently we are working on same type of the project which custom card design online and have the same functions like user can edit the text, images, color at the checkout and select the card size at the checkout.
Hoping for more discussion.