Printed it in 2 pieces with the flat side down so it would be a clean print.
The notches the shells slide into are a little undersized and need some additional trimming in order to get a good fit.
You will need:
A 608 bearing
m2 8 allen machine screws
m2 12 allen machine screws
m4 8 allen machine screws
Cut down spent 45 shells to 13mm
I used this finger cap:
I used PETG, but you could use whatever you want.