Back in the 90's RS (UK) used to sell individual, modular interlocking plastic storage boxes that you could configure as you saw fit. I bought quite a few from RS back then, and I've also recently got some extra modules from school surplus.

I'd quite like to get some more to finish off my storage solution, but despite an intensive search on the internet I can't find anything (apart from possibly 6 modules in Algeria that don't ship to the UK). Has anyone come across these modules, and know where I can buy them. A picture of said modules below.

 

These were made by Integrated Plastics Ltd. in Ontario, Canada. Unfortunately, they went under in 2005.
I have a number of them. If you intend to ever rearrange them I suggest you lubricate the sides and top locking tracks with petroleum jelly before reassembly, otherwise disassembly will be difficult. E

 

Occasionally I do come across them.
How many do you need?

The ones I see have drawer handles that are different from yours.

http://www.championcommercialproducts.ca/html/634-0-parts_cabinets_2.html

 

Those look pretty good. So you can stack, up, clip side ways and get the configuration you want?
I think very cool.