I was having issues with the pins for my Pastamatic slipping loose while I was respooling, so I decided to (crudely) redesign the pins to be snap fit. I am happy to say that they work great for me and I have not had a single pin accidentally slip out since I installed them.
The attached print profile is for a full set of 7 long pins and 8 short pins. I printed in PETG, although I expect PLA will work fine.
The spindle retention clips you see in my Pastamatic photo are the 3rd Wheel Pastamatic Roller Upgrade by toolmantim313. I made snap fit pins for that as well (they are slightly longer than the regular Pastamatic ones) - https://makerworld.com/en/models/200889.