There are other starting points besides 3D printing, arduino/microcontrollers and spark fun sensors. If you just need an enclosure for a product there are read

There are other starting points besides 3D printing, arduino/microcontrollers and spark fun sensors. If you just need an enclosure for a product there are ready-made ones that you just drill and cut as needed. And for anything to do with sensing or automation look into industrial PLCs (automationdirect.com is the cheap supplier) before you start re-inventing the wheel.