Select the end face of the top case half.
In the balloon, click Select
.
Pause over the Constraint tools and select Contact from the vertical balloon that appears.
Select the end face of the bottom case half.
Repeat to create an engineering connection between two side faces.
The two case halves fit perfectly!
Use the smart selection ladder to activate the root structure level.
Repeat to mate the end face of the cap to the end face of the plastic case.
