thats pretty cool on the res idea, hope it works! as for the hole, a file is pretty cheap (get a round one) and will smooth that out a lot nicer! (or can also use the channel idea, quicker and easier I guess ) cool idea for a case! +rep will watch this to see how the res comes out! kind of reminds me of those bubble water toys.
best picture I could find, they make big ones of those things too but I can't seem to find an image! grr.