@JakeHart I think we have a few designs up in Autodesk Fusion360, but I'm not sure if they're public at this time (to be honest, we haven't heard anything from our contacts at Autodesk in months). Most of the designs offer more to the eye than they do comprehensive protection to the board, however.
That said, if you're looking to embed, we strongly recommend the forthcoming Tessel 2 over the original Tessel.
There's a preliminary CAD model for the board here, but I don't want to promise that anything is final until we start manufacturing. The mounting holes should be correct, but I can't guarantee that all of the components (the connectors, mostly) are exactly the right size for lack of dedicated 3D models. Also, never underestimate the power of a simple project box for the first pass, works-like prototype.