Hi George, I have 2 shops, this pet product shop and a vintage shop and I've been using CS in both shops since the beginning too with very accurate results on single and multi-orders.
Until or if we ever get a ships alone button, if I have an item that I don't want combined with something else I do put the box size for the item size but sometimes the problem with this is if you have a bigger box, CS will put 2 items in that bigger box.
If I have an item that I want to ship alone that measures with packing 10x10x6 but I put the item size as 12x12x8 so that is all that will fit for that box and if just that item is bought, that 12x12x8 box size shows up to ship it in.
Problem is........I also have a larger box in my sizes, a 14x12x10.
So it would be possible for someone to buy that item I have as 12x12x8 and say a smaller item and CS would combine them in my 14x12x10 box.
On some really heavy items in my vintage shop, I have done this.
I did a Parcel Select/insured shipping only profile and attached it to my heavier items.
That way if someone buys a smaller fragile item that I only have a Priority/insured profile on, CS will not combine them 2 items becuase they have different mail classes.
I just note on the items with only Parcel Select/insured that if I can mail for the same as Priority I would.
I also put that 14x12x10 box size for my item size and not the item size, so CS won't combine other Parcel Select items with it.