Allowing users to add sections to a web page

I want to create sections (like hero banners etc..) that users can plug into a page/template as they need them. An example can be seen here:

http://gripwizard.com

I want to be able to allow the users to add additional three column sections or heros and change the pictures, headings, and text content (essentially treating each as its own template). I do not see a way to do this with modx. I see that I can define each section in the template and allow them to edit each as a property but that would also entail creating a lot of template variables. Seems like I might be missing something? Maybe this requires a plugin?

I feel like I want to allow the users to add templates to a template.

Any help/pointer is appreciated.

Are the users going to do this via backend or frontend?

Three possible ways:

1. Let each Section be a Resource, managed with Collections, with different templates for each Section-Type and pull them together with getResources or pdoResources
2. Use MIGX, each Section would be a MIGX - item
3. Probably the best Option: https://www.modmore.com/extras/contentblocks/

Thanks! I will take a look at MIGX and ModMore Contentblocks looks promising. MIGX doesnt allow the end user to add new sections to a page on the front-end though, correct?...when I say end-user I mean my clients who know nothing of web design.

If you go with Bruno's solution #1, you could let them edit just the content section in the front end with NewsPublisher.

Is there a special reason, that you want to let them create/edit the pages from frontend?

For Manager users, ContentBlocks is exactly what you want.