Realtalk: I hate printing boxes. I mean, unless you need something super-specific size-wise or you need something with a lot of ins and outs for wires and bolts, there's far better options out there. Even in the case of ins and outs, here's makercase a browser-based CAD program for laser-cutting.
That said, if you do need an enclosure and 3D printing is somehow your only option, my advice is don't half-heart it. Bear in mind, I'm not bashing the brothers Ruiz or anyone at Adafruit; they do awesome work, and I'm not just saying that because I used their trellis enclosure as the template for mine. My issue with their design, however, is it's too lightweight, and too fragile unless you're using very tough material at a very fine layer height. In a factory setting, it's a fragile little buttercup. I need something that can take a beating. It won't survive a two-story fall, but may weather a minor desk-related flooring.
Built Like A Tank