What did I learn….
First. the angles are challenging. I relied on my table saw indicator at first. So the sides are shorter than planned. When i used my drafting triangles and digital angle gauge I got better results.
Second, I should have put something in the groove to keep the glass from rattling.
Third, apply finish to the inside of the pieces before gluing the bugger together.
Aye, agree with all those points of wisdom. Made one not long ago myself. That bugger keep getting smaller and smaller as I trimmed the angles to fit. When it was finally done, the flag barely fit inside.
PS - You may not need anything to hold the glass firm after you put the flag inside.