Print using supports. After printing remove the supports and add two (8mm x 3mm) cylindrical magnets. This will be a very tight fit but the magnets should fit and not require any glue.
My wife got me an Ultimaker2 for fathers day 2014 (best wife ever) and have been having fun doing projects, especially with my kids.
Here are a few things that I have designed.
I also maintain a blog about projects I make with my family:
http...