After working on several water-cooled PCs I built my own in a similar fashion to a design that I made for a customer, using an Antec 1200 case with exterior radiators. This worked great for several years until the graphics card failed (due to faulty memory chips) and needed replacing. I had learned a lot since this initial build and decided that a new, neater case was needed to allow easier maintenance in the future.
I settled on a Corsair Obsidian 750D which I had used in other projects previously. This has lots of mounting options for the radiators and other components that I had.
The whole process took around two days to complete, doing the bulk of the build in my own time between serving customers. The radiators were mounted inside, new phthalate-free tubing was used to connect the components and the whole system was cleaned out and refreshed. The result was much neater, roomier and easier on the eye.