yeah, you want atx minifit pins.

you can get the pins on amazon usually but they're going to be more expensive than buying from a pc modding website. it kind of sucks but no pc modding website has free shipping and amazons prices are always terrible so you're probably out 15-20 dollars no matter what you do.

these are the ones you want https://www.amazon.com/Molex-Female-Mini-Fit-Jr-TM-Connectors/dp/B072KTD2ZJ/ref=sr_1_1?dchild=1&keywords=female+minifit+pins&qid=1613850754&sr=8-1

unfortunately, amazon sucks and 8 dollars for 25 pins is horrible, and you won't use the male pins if you're making the entire cable and not extensions. i probably wasted 100 dollars in shipping when i first started making sleeved cables.