I tried to find some stackable smd boxes and found "SMD SMT Connectable Container". But after printing it was difficult to connect boxes between each other and it takes a lot of force especially if you have little "elephant foot" problem.

So, the first improvement: I've made: the gaps just little bigger and shrink top part of connector to make it smaller. Also I've append little bevel to the bottom plate near gapps.

The wall, containing gap recuced internal volume of the box. The second improvement: I've made double, tripple and quadruple containers and lids (1x2, 1x3, 1x4 and 2x2). Big containers with linear shapes has holders for dividers. It makes you able to use one 1x3 conainer for example as three divided containers or as one big container or as 2+1 containers - just add dividers and lids.

You can use toothpick as a shaft for lid. If you can't insert toothpick into holes slow boring with 2mm drill will help you.