Whew, I pulled it off! Here is how it looks (along with the pattern pieces I created from tracing the original:
I still need to buy some snaps to sew on for a closure. Maybe two snaps - I haven't decided yet. Here's what it looks like with the silverware inside (and flap tucked in for now):
Mr. Mongie has declared it "very cute." If I were to do it again, I would make it taller so that the silverware fit entirely in the bottom of the case and the flap folded flush with the top of the opening.