Summary

Fixed a couple of issues I had with the original design that stopped it fitting together properly:

-Extended one of the jumper cutouts in the top of the case to expose the SMD crystal as this was colliding with the case
-Cut off an extra 1mm from the top of the case at the bottom edge of the chip loader
-Cut off an extra 1mm from the top of the case at the USB port as any wafer overhang from manufacturing blocks the case

Fits together well now on my board without glue, but a bit of glue probably wouldn't hurt if it's going to be knocking around in your storage. Press fit the board into the lower case fully before fitting the top. Also check the solder joints on the USB connector shield, mine weren't actually connected internally and had to be re-melted to stop the port wobbling.