I bought some cheapo cases and foam and cut them for special tools, but you might not be able to find the right size to fit the Assi.
Don't be a quitter, Alx!
Sorry for the late reply. I think I have a tool organisation bug and I'm giving the whole setup a once over
The 'problem' started with acquiring a very nice unused Hazet 3/8" set on eBay, which I bought mainly for its case. The set turned out to be made by Hazet for Snap On (more about it
here).
Initially, I was thinking of replacing the shallow metric sockets in the set with their AF counterparts and deep 12-point with 6 ones I already had - the original sockets, extensions and ratchet from the set would go back on eBay. However, after getting my hands on the box, I realised that selling the parts would be a crime so decided to keep it just the way it was. Except the 6-8 mm, all sockets are 12-point - a slight difference to what I have in my toolbox. There's a few more discrepancies, like ratchet I have is a quick release and this one is not, I don't have a sliding T-handle in 3/8" size and the biggest extension in the set is a tad longer than my other one. So, contrary to my original plan I now have even more sockets and bits to store. As usual. LOL!
The case is not small but it fits on the bottom of the tool cart just fine and with moving all the 3/8" components from the top shelf, I then decided to do it the 'Hazet way' and dedicate the whole shelf to 1/2" and 1/4" stuff.
On a side note, I did away with 1/2"+1/4" combo before and only started acquiring the 3/8" size for special sockets and 'completeness'. It is getting used but not as much as the other two sizes above so it is now resides on the bottom shelf - still easily accessible.
With 3/8" out of the way, I then tried to fill the space by using the bigger plastic insert I had for the 1/2" but it didn't clear the sliding tray for smaller parts, as Hazet call it. The tray sits on top of either of two shelves providing more storage and slides to give access to the shelf content - a very smart solution but sadly no match to Hazet's own plastic inserts. And no matter what I did the sockets just stood in the way. To make matters worse, I've already ordered another sliding tray for the second shelf as I had plans to use them both.
Here's a picture of that sliding tray in case you don't know what I'm talking about. LOL!
Anyway, I scratched my head a little and decided to order this:
Now, because it would look mismatched on its own, I had to order this too (for the second shelf):
The tool arrangment is no different to what I wanted to achieve with my plastic inserts so there won't be any loss nor gain of extra space but in theory it
should allow for both sliding trays to move freely. The foam is one piece so should fill the space nicely. I've never considered the foam before - it looked great but I wasn't sure about the durability or layout, not to mention the cost. Somehow, Hazet plastic inserts offer much better variety at much lower price and generally fit more tools in than foam - I really hope this changes with growing popularity of the Smart Case concept. I didn't end up with just the foam, I had to order some matching tools for it as I would hate it to look empty! LOL.
PS: Apparently, Smart Case is not their most expensive case option - I've been buying some TORX tools for some time now to fill in the plastic insert I had. To my luck, they did exact same design in case form (much more compact too) but the cost was staggering 73 Euros! That's for the empty box and rubber insert.

That 3/8" eBay set in the same size box was certainly a bargain.
The TORX box looks like below and yes, I had to order it and a few missing items too but I should now have a complete set. Result!
Now eagerly awaiting my parcel from Germany. Pics soon!
