In Utrecht, Natuurmonumenten has set out a fun treasure hunt for children and adults, using historical replicas set in concrete for educational purposes.
I made a large steel fibula brooch with sturdy hooks.
They also requested a few replicas of the Trien coin (originally 1.5 cm diameter, in gold)
I enlarged the coin greatly, then etched the design with salt water. Added a few hooks on the back (not visible here).
Steel coins, 6.5 cm diameter