depends on the size of the rep..
most are put in a small box with some moss or damp tissue and then placed inside a polybox on top of a heatpack (24hr one) the poly box is then padded out so the inner box doesn't move and is held safely. air holes are made to let air in to polybox..reps should not be placed in a box too big as there is more room for them to get banged around and hurt..
hmm..i honestly do not know for iguanas! you might have to bag em rather than put em in a box (then put in polybox)....never had one shipped or even seen one shipped...at 9 months it's gonna be pretty big...sorry but i don't think i can help you on that one! maybe someone else can???
some are even bigger! like i said it may need to be bagged and then put in a BIG polybox which is really well padded...but it is a largish animal to ship and it may be slightly different..then again may not! just don't know! sure someone else may have an idea