The roman dodecahedron is an ancient coin sorter. Let me explain.
They were made of cast bronze (expensive), made using lost-wax casting (expensive), and one was made of silver (very very expensive). Where were they found? Military areas, funeraries, baths, theatres, and coin hoards. What do these places have in common? SORTING COINS! Does the cashier at the store put each of your coins in a separate container? Or do they scoop it into a big pile after counting, to be sorted later?
en.wikipedia.org
If they were for coin sorting shouldn't we see wear on the inside?
YES! And we see it's very common with these.
The missing face's knobs look like they dissolved from the inside, their exterior shells remain largely intact
old.reddit.com
Look at this example from Fox News. You can see the inside is extremely corroded and worn, while the exterior is barely even damaged.
foxnews.com
What would be shaken inside a metal dodecahedron that wears it? coins! W
In this image you can see numbers 69, 70, and 139 have the corner balls broken off.
reddit.com
Why were the corner balls broken off? Because the inside and balls are the stress points. They are built thin so they are easier to use. You would operate this by placing coins in the largest hole, with the smallest hole on the bottom, place it on a surface, then rub it back and forth to shake the coins. Smaller coins would be rustled around until they fall out the bottom.