Something to monogram

I think I have found something to monogram, or at least the first something!

This is last year's pencil pouch. I won't even show you the inside it is so gross. But I was thinking I could very easily use it as a template for a new one. School starts today, so if I start right now I won't be that far behind ....

It has been a really, really long time since I have made a pattern from something or even a template - but this is basically a box so it can't be that difficult.

My thought is measure it, then add seam allowances, then make some adjustments for the lining (like 1/4" or 1/2") so that it fits well. And if that doesn't work it isn't a major fabric investment so I can just tweak away!