Picture frame, for about A3 size 'artwork' (Heath End RG7)

Hi, I have a colour print sample that did its job, so worthless now, but it's also an interesting splash of colour I've thought about putting on the wall. It's currently hanging around in the way so I need to find a frame for it before it gets damaged and gets recycled by default!
It's a mostly white card 45x32cm, which is just a bit over A3, and the 'design' is about A4 size so it could be cut down a bit, so any frame for roughly A3 is perfect.
Style wise - not to be fussy but it would definitely only work with a 'modern'/simple frame. Colour could be wood, black, white, grey or silvery metal - just not gold or a colour, that would clash.
Thanks for looking!