OH--simplicity---if your bellows will likely only be compressed or expanded and not inbetween, maybe just a bunch of extension "tubes" (boxes) instead of bellows---extension tubes of different lengths for the different distances you'll need--then you'll have a rigid attachment with now slopping around with 2 standards with bellows inbetween, you know---start offf with one with min extension and one with max extension...or sections of "tube" that can be snapped together or tied together somehow...like stackable containers...one fits in the other...