ASo the bakery I work at is closeing down and they were nice enough to give me all their cookie cutters but a lot of them are very old and look like hell. Just wondering how I should clean them and if I can bring back some life to them? I think they are all made of tin if that matters.

AIf they are tin then probably elbow grease. But I doubt if they are because tin is to soft for most kitchen applications. They are more likely to be galvonised or a mild steel. But given they have come from a professional they could even be stainless. I would try oven cleaner on one or two and if they react ok to the caustic I would use a 50% caustic solution and soak then for about 3 days. (Btw you can't use caustic if they are aluminium ) then wash them up with liquid soap as usual.