Hi, I wrote before you list the domain creating post and selecting the featured image.
Post domain after domain, there is no script, each domain is the different post.
Create post, type the domain name as title, add featured image, select the category or create a new one, write the description for the domain (if you want) and add email form shortcode.
If somebody else want to add his portfolio I just create a new user role and add domains as him.
It is personal portfolio, not automatized site with scripts etc
I also use some plugins to order the domain from a to z and not by the date.
Nothing more. Simple but well looked