From left to right on 2nd image;
1: Round Top
2: Flat Top
3-5: O-Ring Sealing, Plus Cutaways, SAE AS 010 and Metric 2x6mm O-Ring Sized Versions
6: TPU Printable O-Ring Insert for SAE and Metric Sized Caps (Insert so 45 degree angle faces out)
7: Manufactured Cap for Reference
All files are oriented for optimal printing, Caps use between .75-1g of filament each.
Recommend to print in PTEG as PLA isn't as outdoor resistant. .6mm nozzle, .2mm layer height. Should print fine with a .4mm nozzle.
The author hasn't provided the model origin yet.