Initially, I wanted to create one with core, but due to complexities involved in getting the soft iron core, I decided to switch to a coreless version. I came across an extremely useful blog and a research paper(linked below).
I learnt CAD design in 2days and designed the housing. I was unaware that 3D printed stuff can shrink a lot, so i had to use sandpaper to be able make the dimensions proper for the magnets. The CAD files are linked, but maybe don't copy them as they need major changes. 
The motor reached speeds of 4000rpm at around 30% throttle. I decided not to push it further as the 3D printed housing could disintegrate. 
Btw , I am planning to make V2 which will be more compact.