Recently I have found Nanoblocks, a Japanese brick toy, in American stores. How compatible are these with other building toys? They look to be approximately the same scale as Modulex.
It appears that the goal of the nanoblock producers is to make "the world’s smallest toy building blocks"1. And they appear to be too small to be compatible with LEGO. See the following video comparisons of the sizes.
Duplo = compatible with normal Lego even though 2× the size as has hollow stud. Tube of normal 2×2 fits inside. Nano blocks 2×2 being 1/2 size of normal fit with a brick having a hollow stud, e.g. 1 round or 1×1 with holder. But Kawada Nano Blocks don't use tubes, so not fit like this when other makes do. Guess that Nano Blocks' plastic = 1/2 as thick, could only attach Lego by over hanging a corner with it touching the 2nd stud. I've just got some 1/2 size bricks, don't know what brand, can attach under Lego ×2 by having 1/10 on 1 side & 2/5 on the other. Edge of System Lego fits between 2 studs, so can trap between brick & tile.
They also fit end of ×2 Modulex by 2 studs on a corner, if both ends of 2×5 then can join the 2 with nano. Duplo, need to miss every 3rd to avoid the ribs.
Tenté, thinner walls & bigger stud than System Lego, tight fit, not holding when not reaching the edges.
Photo, arms & legs of Lego, head & torso of Nano Blocks. 2nd is Nano Blocks on Lego 1×2's with 1 stud (at 90° to each other) & then Modulex on top.