Multiple pieces snap together to build a lattice structure based on Laves graph. A good general overview of Laves graph can be found here: https://en.wikipedia.org/wiki/Laves_graph
Ten pieces are required to form a “ring,” fifteen “rings” pass through each piece. A single piece surrounded by fifteen complete rings requires 51 pieces. An example is pictured above.
The snaps are designed to favour stability over ease-of-use, meaning they will be tight to connect the first few times until the snap surfaces are smoothed out. If you have difficulty connecting them or prefer a looser fit a few passes over the snap surfaces with a file will do the trick.
Use glue if you want them connected permanently.