Quick word of warning: I didn't check each and every file. Please use common sense and give it a brief look over in the slicer before sending it to print, just in case.
My original goal was to make a modular customizable dispenser system for Multiboard's Multibin system, but found it a bit challenging to try and design stackable inserts... And then I realized: extensions! These can also be used to create stacking bins or a number of other creative structures, I'm sure, but to create a dispenser, choose the Multibin width that best fits your object (2 wide is good for standard 15g gluesticks, for instance), and slap that extension on a normal multibin shell. Then, stack as many normal extensions as desired to hold extra items.
I highly recommend using the Pop-In extensions, as they will be more stable, but I've also included standard click-in extensions of all tolerances. Currently, there are 1 high and 2 high versions of all dimensions and three wall types (topped multipoint rail, full multipoint rail, & simple walls).