Zone System learning apparatus

I was watching the great course "Master MANUAL Metering for Film" by Nick Carver.

I only have a minolta spot meter with EV-value metering so I had to make this.

It requires some paint and glue after printing but will work without too.

***UPDATE***
Added a smaller version of it, only 38mm tall, but less detailed (small_)
Comes with an ISO ring lock (M3 bolt)
I recommend printing 0.1 layer height for better details.

See the pictures for assembly. Glue the thinnest ring to the core centering the V and middle groove of the core. Place the EV-Aperture ring on top of that, then ISO-ring. Finally glue the top part to the core lining the slot and V-mark on the bottom ring. It should have some tolerance so that the rings can turn freely.