Difficulty: either learning how to weld will make this a bit hard, or having someone weld for you will make the cost go up. You also have to know how to use a rivet gun, a power drill, and a tap wrench. On the other hand, you probably could substitute metal epoxy for the welding, since it's not holding much weight...
Step 1: The Base.
Took a scrap of sheet steel, probably 1/16 thickness, and bent in into a C shaped channel that my Zen would almost fit into, except for the control buttons on the side.
Then I ground out the gaps in the edges of the C to allow the buttons to fit.
I took a scavenged hinge and, after a failed attempt on one end(a crappy weld) I managed to Oxi-acetaline torch weld it onto the other end of the C.
Sorry the pic is sideways. Grink! goes my neck.
Step 2: The Lid
Then I drilled the holes for the screws that would anchor it to the hinge, and tapped them with a much-searched-for M5 tap (the school shop had only English standard taps, and my garage was full of metric screws)
Then I screwed it together with loctite, and ground off the protruding ends of the screws to be flush with the sheet steel.
Step 3: The Padding.
The stuff also keeps it from moving around in the several mm of vertical space it has in there.
Step 4: The Clasp.
Step 5: The Decoration
This pic is also sideways. Erk.
Step 6: Afterthoughts....
I believe I shall find either some brass instrument case corners, or some cheaper steel ones and subject them to the flame, and I shall have a less sharp and gougy device.
pics shall follow.........