The concept: choose a shape, drag the size to fit your wall and see it in place. This page is a drawing of how such a shop could work. It does not print or ship anything.
The wall is drawn at one scale. Change the width and the label follows it.
Start from a simple form, or a word or line of the buyer's own.
Enter the wall's width and the page scales the decal to it.
See it against the wall color before deciding.
A real shop would hand the finished design to its print partner.
The studio is a sample. The domain is the real thing on offer.