There is no better way to learn electronics than playing with Raspberry Pi. There are already plenty of cases available for various Pi models. If you know your 3D printing, you can always print your own. Adafruit has shared a video that shows you what it takes to 3D print a TARDIS case for a Pi 3 computer.
A BCN3D Sigma 3D printer was used to complete this with blue PLA. The entire process took about 3.5 hours. More info is available on Adafruit’s channel.