Inaccurate guesswork

Well this is all t6hat remains of 10 sheets of cladding 15x78 cm! and guess what I didnt estimate properly and am now waiting on 3 more sheets to complete the job. I think 2 sheets will finish it but this time ordered extra just to be sure ;)

 This is an unfinished archway.

 here is one almost completed, big improvement I think.

 my arches are not exact lol a little like my guesswork,so I put matt board behind the arch and traced the shape onto it.

 Then I decided what thickness I wanted the framing to be and cut 2 straight lenghts from matt board the desired width.

 I then ran along the edges with an embossing tool to soften them.

 The straight section was then used as a measure to draw the thickness of the arch...by simply placing ,marking,placing marking etc then joining the dots.

I then used this as a template for the other side of the archway. The matt board was coloured with a furniture touch up pen ( thanks to MiniAussie) and a small piece of matt board cut to cover the join.I must get back to my shingles now ....oh and the egg cartons are back out for another job this week.