Need suggestion for a pet memorial

Hey all,
I am starting a pet memorial, pet loss and grief website soon where people will be presented with a form which will have all kinds of details but most importantly there will be 3-4 image selectors such as:
First: they will select an area. like a mountain, beach, or snow.
Second: They will select a memorial stone.
Third: They will select toys to be placed next to the memorial stone.
Fourth: They will upload a pet photo to be placed on the memorial stone.

When this has been done and page is submitted it would make one picture combining all of these. I hope that makes sense?
Its like that wp configurator thing where you select bunch of stuff and it makes a pic but I cant find a plugin or tool that could do this with a form such as gravity.
I need this to be saved to files and database so then user can pay and later be able to edit it (custom post type).

Any of your help is greatly appreciated I know its a difficult one.

I will try to simplify.
I am trying to use gravity forms and image choices addon to receive user submissions and automatically create a post, but I want every choice of image to be combined or made into composite image. I know imagemagick can create composite images but I need this to happen automatically.