Is there an iPhone app where you can design a signpost?

Yes, there are several iphone apps that allow you to design a signpost. Here are a few options:

Canva - Canva is a popular graphic design app that offers a wide range of templates, including signpost designs. You can customize the design by adding your own text, images, and colors.

SignMaker - SignMaker is a simple app that lets you create your own custom signs. You can choose from a variety of sign types, including street signs, parking signs, and warning signs, and customize them with your own text.

Signpost Studio - Signpost Studio is a dedicated app for creating signposts. It offers a range of signpost designs and allows you to add your own text and icons.

Sign Creator - Sign Creator is another app that lets you design your own signs. It offers a variety of sign types and allows you to customize them with your own text and images.

There may be other apps available as well, so it's worth browsing the App Store to see what's available and finding one that suits your needs.