we've switched to 4 leg sections for shorter collapsed length or longer suitcase if using 3 section pods. Then we dismount the heads and put it all in our regular baggage.[a href=\"index.php?act=findpost&pid=208704\"][{POST_SNAPBACK}][/a]
I've been on a similar path:
My main tripod is a 4-section carbon-fibre job, and when flying the head gets removed and the legs are put into a PVC tube. This was built out of a section of stormwater pipe, with caps on each end. It's not meant to be waterproof/airtight (in fact there are small holes drilled into it to equalise air pressure). One cap is taped into place, the other is pushed on / pulled off, and a piece of soft foam stops the legs from sliding around. The top section of the legs have Op/Tech foam wrapping, so it's a quite neat fit. There's room for a few other things in the tube, but packing it tightly with other stuff could cause hassles during baggage inspection so I tend not to do that. If I had a metal tripod I might not have worried about protecting the legs in quite this way (CF is most susceptible to side impacts) but since I built this a few years ago I've been very happy with it!
The tube is placed into the duffle bag (which has roller feet at one end) I use as my usual check-in luggage, and my clothes and other gear is packed around it. The tube does add a bit of weight, but I haven't had any hassles with the duffle bag being overweight. I could have used a hard-sided suitcase and avoided adding the tube, but I've been happy with the flexibility of the duffle in schlepping around airports, squashing it into taxi/bus/train luggage racks, carrying up stairs, etc.
There's no clue to baggage handlers that there's anything special about the bag: it's just another piece of luggage. And when I get to my destination if I'm in a car I often take the lid off the end of the tube and put the tube in the footwell behind the front seats. It provides a neat "holster" to slide the tripod into while driving around, without having to worry too much about water/dust/mud on the feet.
Thinking back on it, I cut the tube to the optimum length for these tripod legs, and then took the outer measurements of the tube with me when shopping for the duffle bag. But the bag wasn't expensive, and if I start using a different tripod I can build a new tube very cheaply.
Re-reading the OP's request, you may be looking for something for shipping multiple tripods and this solution might not suit you. But for individual photographers travelling with their own gear it's worth considering.