I just recently got some foam too and thought I would share my solution.
It was 1 tactical backpack and 2
gw cases. This was best for me as it was a bag I could use to carry a number of things like lots of books for role play or 2 cases which is enough for a 1500pt
40k army as long as you dont go crazy with vehicles. The standard foam is fine if you don't have alot of metal minis. But the good thing about this if I only need to carry one case for my fantasy army then I can crumple the bag down to 1 case size. This is really what made it appeal and I liked the pack 432 but it was too small for a
40k army and the pack 720 was too big to carry around my dwarf army who only need 4 inches of foam.
Also custom cut foam I can only see being useful for metal models that can move around alot. Standard sizes allows you to reuse the foam for other armies as well.
Finally with the
GW case size being so standard every foammaker makes foam for it so you arent locked to one supplier. For
example I use KR foam as its quite cheap.
All up I am very happy with the solution.
The part that sticks out can be crumpled in when you only need 1 case.
I got one of the cases from the tools pack which was quite a bargin
This is KR 4 inch pluck and pull I hadnt put together my 2nd battle wagon yet. theres 4 deep pockets free, for future expansion or tall banner minis. I plan to put padding foam around the open areas of the truck and copters to minimise movement.
This is the standard
GW foam its easy to cut and a good size for the orks, I also have a KR pack that can fit 40 minis in either 1 inch ir 1.5 inch. I plan to use the KR foam for my dwarfs.