These are REALLY cute. I really like what you have going on here.
Is the grid in the top images supposed to be a net or a wire fence? If the latter, I have a hard time believing they could bend it that much. If the former, why are they climbing on it? I guess I just don't quite understand what is going on or what the location is in that first one.
I feel like there should be some sort of support to the bar they are sitting on in the second.
I love the third! Maybe as an artist I just think its the most fun. I would move both the artist and the other two a little bit closer to the center though--I know you should stand far from your subject when drawing, but the middle just feels a bit empty to me.
Those are just my gut reactions. Overall, great work, I really like your designs here.