Through the last 6 years working as a designer and studying an MA Design, I have collected a library of 'design thinking methods'. I have them on a first edit in an evernote notebook presently. However, I have the urge to release this knowledge somehow. I think it would be a really valuable resource to be built upon. However, the question is, do I get it edited / or edit it myself, and then produce a book, or do I go for an online solution. A lot of the techniques lend themselves to being built upon and having people writing into them. However, I'm not that familiar with what online options I have for this. Any suggestions as to what format could work?
You could use a wiki, which would open the information to others while also inviting contributions and edits.
I think you are not doing it in the write way. Why thinking in how you will distribute a work that does not exist? First create it, then handle the distribution. Having notes about something is not the same think as having a work ready to be distributed, and I'm sure you will find it more complex to change the notes into a book that you may think.
The main reason I'm talking you that, is because your work will determine how you will distribute it.
Imho, the first try is always to get published by somebody. You may not like the conditions -- and you are not forced to accept a publisher's offer -- but you will get some kind of feedback on how good your good is, and you will be able to decide if the low profit -- about 10% to 15% -- payed by a publisher compensates not having to invest your own money and having all the trouble inherent to self publishing. After having feedback of a publisher, you may decide to go on or choose another option.
Also, it helps your curriculum to have a published book by some specialized publisher -- since you want to write technical work -- more than choose to proceed with your own. Sometimes this may compensate the lower profits.
Of course, to have that option, you will need to show your work. To show your work, it must be finished unless you are so well know and/or have such expertize that may get the interest of a publisher to a project.
Self-publishing has its advantages, but also its risks. If you have a lot of connections that may be interested in such knowledge, can give workshops where you can sell, and have means to promote yourself, it can be a good option. If not, I wouldn't advise it.
Online publishing is a solution I don't like. It's growing but I don't see it with so much acceptance as paper books. Also, it doesn't provides so much recognition as physical books. Some may disagree but, I'm giving my personal opinion.
Online publishing has its own formating rules. They are easy to learn and I think the best publisher is Amazon. You will find them all easily, and you can publish in a lot of sites since most of them are not exclusive.
Resuming, I think that, after having the finished manuscript, you should weight the pros and cons and decide what path to follow.