Service for cases or enclosure

I’m working on a project to control the brightness of a strand of LED’s. I would like to have it in an enclosure to protect against damage, shorts, also to make it look nice. Is there are service that will build a simple case or enclosure?

The board has a power jack, Ethernet port (for a BeagleBone Black), and cables to the LED strand. What details do I have to figure out before I can get an enclosure made? Do I need to worry about strain relief? How will I mount the board? What information does someone need to design a case? How much does a low volume case cost?

I don’t have all the answers, but I do know of some places you can get a quote from: