Question: I'd like to create a custom drag and drop template so I can increase the design possibilities without losing the functionality. I can't find anything in their documentation.

I was hoping to create something like [this](http://i.stack.imgur.com/KhAd3.png), not sure if I'm missing something obvious but I can't find a drag and drop that allows for the different coloured background with columns too.

I could use a block of code but I can't edit the css styles so it wouldn't be responsive for mobile and also not very friendly for those who don't know html.

Answer: 
Rather old question, but to who it might be helpfull: 

If you code your own template and upload it to Mailchimp you lose the 'drag & drop' system/UX interface with the different blocks. You are able to create repeatable blocks but then it works with a dropdown list. This is (in my humble opinion) not that user friendly and takes a while before you fully understand how to use the dropdown. I had to explain it to a client earlier today and took a while before they understood it, so I decided to write them a manual for it. 

But the design you want to create should be possible to make with a standard MC template. In the 'design' tab you will find settings to control background colors etc.
I know this is an old question, but while searching for this myself I stumbled upon a solution posted [here](https://stackoverflow.com/a/41620134/3041866).

Basically it is possible to code your own drag n' drop template, but the solution has not been documented.

1. Find one of the Mailchimp templates (either one of the basic templates or a custom template from the 'Themes' menu.
2. Use 'Inspect element' and copy the source code of the iFramed html-email.
3. Paste in your preferred HTML-editor and modify as intended
4. Create your own template from the 'Paste in code' mode
5. If you want custom modules to be added by default, edit using the menu 'Edit design' in the bottom of the screen.
6. Save and exit :)