This item is a educational construction kit assembled from various materials (plastic, metal, etc.).
Assembly Guide
'Push rivets' to be used in -- well, holding things together! Part of Tamiya's Educational Construction series of kits and toys and other things to provide projects for students during their summer break, these rivets work very much like drywall plugs -- the plug goes in first, then the 'rivet' is inserted, the plug splits, and the joint holds securely.