This flightcase is about the size of a 4x12, and very well built.
It's left over from when I bought some gear. It's currently got foam/partitioning to suit an old Roland mixer, but if you remove that, the maximum internal dimensions are: 770 x 720 x 300mm. Some road wear, but the butterfly fasteners and handles and alignment are all OK.
£15 collect from Cambridge.
10 packs of Jaffa Cakes.
New crazy low price: 5 packs of ginger nuts.