One of the sides of my wall is around 10mm off level to my door frame as I built up 3 layers of plasterboard with tecsound in between to lower the noise transfer, as this is a home office. I was thinking about how to fill this gap with a strip of wood, but I need to plain it at an angle and I've no idea how I can best achieve this. maybe there is a DYI friendly tool to assist with that? I was thinking even about using a wood filler, but I guess it would be too much at the top where the difference is 10mm, but maybe at the bottom where there is little difference it would work? I hope the pictures help getting a better idea? Thanks!