[trekkor]

Take some measurements. Plan ahead.

When setting up you plywood frames you need them to finish without sheet rock, the same dimension thickness as the wall framing.

So, maybe 1/2 ply + 2 1/2 wood + 1/2 ply to equal 3 1/2 if it's 2x4 framing.

I'd attach the 2x to the head and run the verticals down to lowest point of your arches with a taper at the bottom for the arch shape.
Put the plywood on and then ad blocking every few inches along the inside of the arch. use a framing nailer or screws. Hand nailing would be a nightmare.

Attach the sheetrock as a rectangle and dremel/roto-zip in place.

Use the flexible round corners and let them overlap the existing corners. One layer of 1/4 sheet rock on the inside of the arches should be great.

Don't rush...ask questions.


KT