Thanks for sharing, this is a cool idea for a cheap organizer.
I was just thinking - for transportation, rather than removing all your tools and putting them inside, you could leave them in the holes, and use the lid from the second container to place over the top, and just use an elastic or some lace to hold it on and keep all the tools in place. Would save you tools from being banged up, and save you having to reorganize a bunch of stamps every time you move them.