Although I have actually been able to make a sidewall bubble once in a while, I do have a lot of trouble with them.  I am wondering what the benefit of that over the raison twist is.  In a heart shape I can understand the bubble's advantage in the distortion but in most cases would a raison twist work and if not, why not.  Trust me I am not condemning the sidewall bubble I am simply curious as to why they are used in lieu of the raison twist.

Having just watched Buster Balloons spike the dog being made he notes that the side wall bubble gives a slight distortion on the balloon which gives a unique look to the dog. With David's mask is the same I think as it gives a distortion in the 350. Just my thoughts I am sure others will have some :-)

Yes, I'm thinking that's the reason as well.  I would like to buy that dvd "Spike" as I've wondered about how he does the feet.

If you struggle with the side wall bubble I think someone here suggested putting a small bubble or a bouncy ball inside the balloon,
gives you something substantial to get hold of when attempting the side wall bubble.

Funny, I thought about that Graham but I wondered if it was cheating.  Although, who would know but me right?