Thread: Cutting a die

I'm sure this has been discussed before but I don't remember what the consensus was. I'm referring to modifying pre-existing hardened dies, specifically trimming the bottom off by a few mm's.
Is this at all possible? Or is it just very hard work on the cutting tools?
Don't ask why... I'm just mulling over options for a wildcat, and wondered about how hard it will be to trim an existing sizing die instead of making a new custom one.
Cheers in advance chaps