I use a bit thinner material (about 22 gauge), but using decent metal shears, it's not too bad. Odd shapes can get quite tricky, but it's not too bad if you split it up right. I also only cut a few pieces at a time, so I don't spend hours at once cutting. I haven't used a plasma cutter, but it might be difficult to get the right shape by hand, that would require a cnc plasma cutter which is a bit more difficult. I don't know if this helps you with motivation, but I try to build up a part just tacking it together and then weld and grind it all later, but when I can still reasonably do it, but I have issues with motivation to grind or weld, as I have to set everything up for that, whereas cutting doesn't require much. It can also sometimes help to have something to look at that pushes you through, like the helmet.