CactiGuide.com

I purchased what was described as a M. Carretii in 2018, which is actually, I think, a M. Picta sub. Viereckii, principally due to the white spines and the fact that it's winter flowering.

https://cactiguide.com/forum/viewtopic.php?f=3&t=42412

So this winter I'd like to see if I can get some seeds out of it and would welcome any tips as I can't find much information on this plant.

The main plant and offsets are starting to develop flowers (there are another three new offsets it's thrown out in the last few months on the other side).

Most cacti are self-sterile, so you will need another genetically different (i.e, not a cutting or offset of your plant) M. picta to pollinate your flowers and produce further "true" M. picta seed.
If you don't have one, you may be able to produce hybrids using another Mammillaria or closely related species.
Pollination requires the transfer of pollen from one flower to the stigma of another flower.

Thanks, i did wonder if it would work from an offset. I guess i won't be pollinating a picta this Christmas. No problems though, it's doing well and producing plenty of pups.