if you have access to a router, you can possibly do a "poor man's" milled wood case.
Get two blocks of nice wood and route the outer and inner dimensions of the border, deep enough to fit the board into. then just route smaller and smaller in a spiral till you just have the center to route out. Hand sand the outer surfaces, drill and file to the desired shape, any holes (such as USB). Predrill the screw holes... If you don't you might crack the wood, after all that work. For a trim piece, to cover the edge of the board, you can do a couple things... The cheapest, easiest, simplest method could be as simple as buying some ready cut trim/moulding pieces from the hardware store and attaching it around the edge, so it goes over the top edge of the keyboard. do a miter cut at the corners, and your good.
If you don't have the router even, then it's STILL possible. You'll want to get some thin pieces of nice quality wood. You might be able to even have your local hardware store cut the pieces for you, if you don't have a saw, but a hand saw will do, if you are very careful to keep your cuts nice and straight... Go slow and steady. you want to cut the four sides, and the bottom plate. You can screw the sides to the keyboard PC board, and the bottom to the sides. This is actually similar to what I'm doing with my own keyboard. I have an anodized aluminum plate, and I will screw it to four lengths of thin wood around the border. I'll then screw a solid plate onto the bottom of that wood border. A dab of wood glue in the corners of the wood border will hold it together, even when the assembly is unscrewed. This method is probably easier than the router method, as the only tools really needed are a saw (even a hand saw will do, if you are steady), a ruler, a drill or dremel to make the screw holes and the USB port, and sandpaper, a file, etc to smooth things up. Most of that can be had for really cheap at any hardware store. You may even be able to avoid sawing wood if you can find trim/moulding pieces already sized to your preferences. Then you just only cut the wood into segments, which is MUCH easier than cutting strips out with long straight lines.
Basically, if you have some basic tools, you can make this happen. You might need to spend an afternoon browsing your local hardware store or lumber shop for ideas on what could come together, but you should have something form into a workable idea.
If you have an actual mill, then you're more than set to make something like that, and could even do it in metal, but most people don't have a mill... Speaking of... I REALLY need to fix the Z axis of my mill... Quill is jammed in the down most position, ever since I moved it. I suspect it's just a small bit of debris inside it, but I just haven't had the time or space to unpack it and check it out, or to set it up.