When plugging a hole with a shaving, it’s important to try and match the curvature of the arching to avoid reflection problems.
I start off with a split piece of old pine, make a rough template of the arch and transfer it onto the piece. I then split away more wood to follow the line and create a shaving using a chisel, file, gouge and scraper.
The edges of the hole are feathered out and the shaving is just slightly larger than the hole and gets glued and pressed into the area in the cast.
Iris Carr Restorations 