I have 2 Hamatocactus hamatacanthus with seedpods that I want to save seed from. Do they turn red when ripe like their cousin Hamatacanthus setispinus does? Or do they turn a brownish color and then dry when mature? I really don't want to miss the seed collecting opportunity because I have a nephew anxiously waiting for seed. Like me, most of his collection is grown from seed.
The seeds will stay viable for ages, you don't need to be in a rush to collect them. I'd just wait till the seed pods start looking dried out, then collect the seed.