Just start with some general purpose 6013's. But buy a decent branded rod rather than the generic tool staton rods as these will make it much harder to learn.
I would probably use a 3.2 rod for that box, but you might find a 2.5 easier to learn with.
Why use a 3.2 rod on 2.5mm thick steel? Surely that is going to be much harder than using a 2.5
I've got some 25x25x2.5 box to practice on if that's any good.
The set won't handle bigger than 3.2 mm
Esab. Murex are commonly available in 6013 siftrode are said by some to be ok I have only done one box of 7018 in them so won't comment
It's not too bad an idea to burn your way through a full box of something like super six on scrap
If your on a 13 amp plug better stick to 2.5 mm
6013 definitely not 7018 or other lohydrogen too hard to start and re start for a first go
According the weldequip site
"Rated at 16 amps fuse supply to obtain it's maximum 160 Amps output, we managed to run a 4.0mm 6013 electrode at 140 Amps from a standard 13 amp supply without any problems. Other machines from the same factory, under different badges, require a 25 amp+ fused supply to be able to run at maximum power"
I'll go and get some 8 to 10mm plate to practice on.
Can't wait to give it a whirl.
I enjoy the sound of a machine working, fan noise is therapeutic to me!
Once youve purchased your rods, when not using them, keep them in a warm dry house, not a damp shed. The absorb moisture.