John Barry
pfm Member
I've given up trying to cut mounts, so now use this company (others will be available) for non-standard mounts. They will cut to the mm and are accurate. Their framing is also excellent, with various glass / acrylic options, although like most things their prices have increased post Covid:Annoying things. Mine is very slightly out of true, which is incredibly frustrating when leaving a gap between the image and the matt, as I've done here. I should have sent it back to Logan, but I left it too long.
https://www.easyframe.co.uk/picture-mounts