Last time I flew, it was "liquids" they were after, that had to be the 1.5 oz. or whatever ridiculous size. They didn't let me take on a bottle of Listerine that was over the limit, but a tube of toothpaste that held twice the volume, and was opaque so you couldn't see the contents - and a new jumbo deoderant stick (the 'gel' type) were just peachy. I bet the small silicone tubes aren't on the stupid 'might be an explosive component' list - even though something goopy and thick spells higher density to me and therefore higher overall stored energy potential, from my admittedly small chemistry knowledge.
Good old UK even bans large tubes of toothpaste.
I used to use a ridged Samsonite case which would take Subal housing, 3 strobes and all such as carry on. Yes, overweight but got it through. Then airlines from the UK started getting tighter and it went into baggage leaving me worried it might not arrive so ruining a trip.
Now with even tighter regulations, lower limits, my last trip I took a Nexus D200 housing with one handle removed, macro port and camera inside as carry on in the lightest weight backpack I could find. This just came in at 6 kg the UK weight limit. Gave me something of a possible working setup. The rest had to be in baggage. A pain to reassemble but no way around it that I can see. We are only allowed one carry on of any sort, everything must be in it at under that 6 kg.
Weight limits cuts out items I would normally consider essential safety equipment (like DSMB and spare, strobe flasher, larger torch - flashlight, regulator for pony) and for some trips even my regulators and BC have had to stay behind.
Charles Stirling