Hey, cool stuff. :]
We do have a sig critique thread though iirc. I never go in there though because I'm mad garbs at photoshop.
No reasons I can't still provide some CNC or whatever.
Compositionally, there's not much going on. The last Peach one is the most interesting - probably because it's the only one that doesn't have an image splitting the compostion up the middle. Symmetry is boring to the eye. It's very static and doesn't lead the eye anywhere.
Your texts also seem to just be pasted on, and it seems very flat. Again, the peach one isn't so bad, compared to say, the goomba one that just has a flat white text that doesn't match the rest of the sig.
The color schemes are alright (if not a tad typical.) Take risks with color and screw around with stuff. I learn a lot just by messing around, and sometimes you might get a happy accident.