I realise you're coming from a position of skill and experience, but it looks straightforward in the sense that you have a square window, and then you make the frame square too that, and use the packing to mitigate the wonkeyness of the building.
Is that it, or are there a number of other factors that complicate it?
It’s basically simple, yes. Mainly about designing out problems rather than embellishing. If you wanted to replicate it I’d suggest talking to a cabinet maker or finish joinery type person. A builder would fuck it up.
How hard is this to do?
I realise you're coming from a position of skill and experience, but it looks straightforward in the sense that you have a square window, and then you make the frame square too that, and use the packing to mitigate the wonkeyness of the building.
Is that it, or are there a number of other factors that complicate it?