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.
Still not possible, answer from the Mailchimp support: "At the moment, it's not currently possible to code a drag and drop template completely--one of our drag and drop template layouts will need to be selected, but you can drop in Code blocks to get a little more control over the styling of certain sections."

Though, if it's any help, it is possible to fully custom code your own template, and then add in mailchimps special Template language to the template to open up sections as editable within the campaign builder--or even duplicate certain sections of content. It's not quite the same as the drag drop templates, but adds similar functionality. More info on working with template language can be found here: <https://mailchimp.com/help/getting-started-with-mailchimps-template-language/>