I think that if I had printed it in ABS and there was a percent or so shrinkage, it would have been tight - I printed it in PLA and it was a perfect fit - the Pi slid right in with zero effort.
The end cap has to be crazy glued on - I think I would look at changing the cap to use a friction or spring fit of some sort if redesigning.
For thos eo fyou that missed it - the time lapse it here:
http://youtu.be/i-Cw_J5svqk