Well, at 39p per pack, the litmus test is to order some up & test - they have a minimum £10 order but therere site is a veritable cavern of all things shiny to me so that won';t be a problem!

The carbon content is of concern - best way is rather than debate it (I reckon at 39p they'll not be that hardened) ...just to order some up.

re cutting them - not intimidated at all - I've cut Alnico before (the hardest substance in the universe - just kidding ok!) & survived - I made up a little dremel holder for my tool post & used that to slice into it with the dremel cutting discs....it worked well. But hey, if they are hardened, yeah...then I may just stick with 5mm bog standard mild steel & a nickel plating kit.

robin, you asked how I'd holding the pieces while plating - I was thinking about lobbing the small pole pieces in a copper mesh bag - plausible?

A corrosion resistant finish is important - but maybe I'm getting a little over worked up about it - for example I parted off some basic 5mm bright steel pole pieces about 6 months ago - some of these have laid in my cold, damp loft for 6 months - no rust.