Probably the best answer to what the OP originally asked for – those cases are a bit crappy for their intended use – the clips don’t secure well enough for carrying them around loaded up – but its a cheap way of getting the little compartments inside.
Screwfix also sell screws in cases that have similar (but not similar enough to be interchangeable) compartments in them, which would be a cost effective way of getting the compartments if you need to buy screws anyway
I’d need 10-15 or varying sizes if possible
I’m slowly replacing some cases like the ones linked to by Rockthreegozy with sturdier Stanley Fat Max ones. So might have a fair few of the little compartments surplus to requirements soon