Barb, you are going to be a Pro at angles once done. Your flag case, now this. :-)
When I am not sure of an angle, I'll often use paper or cardboard to make pieces I can move around to get the look I want. Then I'll use an angle finder gauge, there are many types on the market, I like these.
Let us know what else you need. Seeing it in your head is the hardest part sometimes. Being able to see into yours to understand which part you don't understand is the hardest part for us.
