Is possible to allow your customers to upload the images in different formats, via Printing Methods > click on your printing Method and check the flag "Allow users to upload their own images". (see below)
Your customer can upload the following formats:
- JPG, SVG
- PDF, EPS, AI (addon required)
or can use the images from Facebook, Instagram, or Premium Photo.
The customer side button will have the description based on the chosen formats, for example, in this case, having selected PDF EPS and AI, the button to upload the image will be displayed in this way: