These very distinctly remind me of electric/electronic didactic "toys" from the at least 80s. Plastic cubes, containing a single (usually) circuit component, like switches, resistors, lights, coils, or just wire, with bare metal connectors on relevant sides and a symbol on top. You got a whole bag of them, as well as a gridded board you inserted the cubes into. Could make even usable stuff like simple radios.