RE: good for something...
Good idea. The tube ( round or square ) is of course sharpened on the inside.
There was a whole 5 page article on making proper punches from silver steel by Alec Whittaker in the English magazine RCME January 2009.
Lots of info including the important point of having a soft pine wood underneath as an anvil. Also could be punched halfway and the wood turned over to complete the cut to cut cleanly. Some people wet the wood to soften before punching in kit production it seems.