The foam is fixed in with spots of hotmelt glue, this looks messy if the foam is pulled out so I'm leaving it in to start with.
I can get all of my kit in the case:
1x red
2x blue
1x gold of Simon Hopes handles each with a tool inserted
1 each crown cryo bowl gouges in 1/2 and 3/8 (The half incher is a decent sized tool and the 3/8" is the Ellsworth with it's v. long handle)
6x shorter tools (40-45cm long) with their fixed handles (roughing gouge, parting tool, couple of skews, scraper, etc)
Half a dozen unhandled inserts to fit the hope handles.
That fills it and It makes for quite a heavy boxful but closes up fine. I'll throw in a big bag of silica gel to keep the tools happy in storage (50 gram bags of orange / green are working great for me now I've learned how to dry them out and regenerate them in the microwave in about 15 mins - the trick is 1 min on full power to get them sweating, followed by 15 mins on defrost setting so they don't overheat and melt the bag).
I'm going to try and be good and not collect lots more tools, but if I fail there's the option to pull out the foam in which case I bet I could fit nearly twice as much in.
I should add that the tools have to be top to tail. If you're worried about edges, slide a bit of plastic tube over the sharp ends when putting away.
I was looking at making a clever case out of birch ply that would close for transport and open up flat and hang on my french cleats to work out of. The decathlon box is so much lighter than that would have been. Decently tough and resilient enough to cope with the knocks.
You might also find an aluminium flight case style thing meant for a gun or a small keyboard as another option but much more expensive.