I printed the items on a Prusa MK3S using Taulman PCTPE, a filament combining the toughness of Nylon and a thermoplastic elastomer; if you use ordinary PLA the rings may crack due to brittleness, and if you use TPU, the rings may be too squishy to hold properly. 

You will also need an M2.5 screw about 10mm long and one M2.5 nut.