Motif on the obverse: the inner part of the core features a cube geometric shape that resembles the cube on the official logo of the Croatian Association of Technical Culture, carrying the message of stability, endurance and geometric perfection. The cube symbolises one of the fields in the coat of arms of the Republic of Croatia, while the twelve identical cube edges represent the equal number of the fundamental principles of the Croatian Association of Technical Culture. The anniversary years “1946” and “2021” are inscribed in the centre of the coin core and the cube, while the remaining part of the coin core features the components of a circuit board as an important part of many electronic devices. The inscription “75. OBLJETNICA OSNIVANJA HRVATSKE ZAJEDNICE TEHNIČKE KULTURE” (75TH ANNIVERSARY OF THE FOUNDING OF THE CROATIAN ASSOCIATION OF TECHNICAL CULTURE) is laid out circularly within the ring. The upper edge of the ring features circularly positioned clips, individually representing different technical culture activities and linked together making a chain, the symbol of strength and unity in the development of technical culture.
Motif on the reverse: the centre of the coin core features the stylised denomination numeral “25”. The outlines of the number “25” reveal an image of a marten turned to the right, with the marten’s body integrated with the denomination numeral. Positioned above the denomination numeral and the image of a marten, on the coin’s core surface, is an image of the coat of arms of the Republic of Croatia. The name of the monetary unit “KUNA” is inscribed below the numeral within the coin’s core. The inscription “REPUBLIKA HRVATSKA” is laid out semi-circularly above the coin’s core, on the surface of the coin’s ring. A laurel branch in bloom is positioned at the left below the coin’s core, on the coin’s ring surface. A common oak branch with acorns is positioned at the right on the coin’s ring surface. The upper edge of the ring features circularly positioned clips, which linked together make a chain, with the same symbolic message as in the description of the motif on the obverse of the coin.
