Its a commission option that was started years ago, originally something 'Quick' such as sketches or colored sketches, but at this point in time its really up to which artist opens for them.
Back then it was like a 'challenge' usually upwards of 100 slots, which is why they were usually more simple in style (like less shading or slightly sketchy lines) that lets the artist finish them faster
But again these days 'Iron Artist' is what the artist wants them to be by their choice.
1st Journal says how many slots are available
2nd Journal says who's been picked
Its a commission option that was started years ago, originally something 'Quick' such as sketches or colored sketches, but at this point in time its really up to which artist opens for them.
Back then it was like a 'challenge' usually upwards of 100 slots, which is why they were usually more simple in style (like less shading or slightly sketchy lines) that lets the artist finish them faster
But again these days 'Iron Artist' is what the artist wants them to be by their choice.