What is it designed to store? It’d be easy to design something like it to 3D print.
It is designed to store sealant cartridges (silicon/caulk) in Festool systainer boxes. I found it in Festool Australia Website long ago. I would like to have a similar one for DS400 DeWALT Toughsystem tool box. Clear/White/Black/Brown/Grey/Beige/Heat resistant silicon, No more nail, GripFill, Caulk and many others. It is easy to get them if they are stored vertically. I know you are good with 3D printing, I have seen your works in other websites also. Specially DeWALT Toughcase+ Jigsaw blade plastic holder you made was amazing. Maybe you can make one like this for Toughsystem tool boxes 
Does not need to be made of foam.
Price wise - and I don’t know how true this is - but perhaps that would be cheaper made out of some wood.
Thinking 2 pieces of 7mm or thicker ply - some short standoffs made of 1x1’s (25mm x 25mm) or some such. and then the holes drilled for the tubes with some holesaw. Might not be pretty - but I would think it could be cheap and in your hands quick.
and also a decent idea.
The thing is if the hole for the sealant cartridges does not have a full wall (as there would be gap between two plywood sheets in your suggestion) it might not sit in the hole in the bottom plywood easily, can be sometimes annoying if you are in rush, I don’t like the idea of foam also. as it is not easy to keep them clean, they can get destroyed easily and also by time you breath small particles from them, I would like to see it as a solid plastic piece with holes on it, it would be much smoother to shaft the cartridges in also.
would a common size PVC pipe (or other plastic pipe) fit the tubes. maybe make the plywood thing with plastic tubes in there. They would be the support and they would have a constant column for the caulk/glue
It would work probably, but that would take lots of time, if it is going to be a factory made plastic product the cost would be less, and probably it would be sold for maximum 20 USD. I would not waste my time to make something like that. I will wait for a factory made one.
My concern is you might wait a long time.
looooooooooooooooool In some cases I did wait for a long time. You are right, DeWALT is quite slow in developing Toughsystem tool boxes. These are made of plastic, not omplicated or difficult to design and make.