The gas cap is great when its new, but when it gets used it fills up with crud and doesn't work right. I have a few suggestions:
This one is a little weird but you should make a 'bubble' in the top of the gas tanks on the blowers so that if you fill the gas almost to the brim it just displaces into the bubble instead of coming out of the tank.
On some of the stuff (BG86 especially) the black plastic stuff is bad. The spark plug boot always gets filthy and makes the rest of the machine look bad. You should make it a different, less sticky material. Also the handle has a little bit of the same problem.
Once again, the recoil starter on my bg86 get a little in the way as you walk. holding the blower with your right arm straight down, every step you hit the pull handle and it shakes around. Now on the housing of my blower there is a circular line etched into the plastic where this rubs up against it so much.
thats it for now....