Initially just the reservoir. Maybe using a diagonal filter to push the rings aside to prevent the rings entering the loop?
I have to be honest I’ve never acutly thought out the logistics as it seemed impossible to do. The reservoir needs to be custom made and as far as I know no one provides a service like this
Wow, orcs and elves is actually a great find!
That and Fighting Fantasy where, perhaps, the best first person fantasy games on the system.