There are a few ways you can do this depending on how ethical and stable you want your preservation to be. Naturally, you are going to want the best of the best, let’s be real. Unfortunately, you aren’t going to find too many people giving that information out for stable, well-established formulas.

Some are more ethical than others, but if you are making it yourself you are well in the know of what you are putting into your piece.

This DIY method is easy and you can get most of the items quickly. Please note this method is NOT professional grade.
You can see the below method done on a previous blog post or my YouTube.

Resin
You will want 5 ml of Citric Acid
5ml of breastmilk
(titanium dioxide) if you choose
Mix together and evaporate off the liquid in a double boiler method until the mixture becomes a paste.
Flatten onto parchment paper to dry for 1 week. Silica gel sand helps this process as well.
Once dried mix with your resin and cast. - I recommend sealing your piece to give it extra protection.

The famous powder dust is made with various ingredients. Most are not public, but I speculate a lot of them are filled with titanium dioxide, plaster, citric acid, and other finely ground powders. Most of all, whatever they are using is highly pigmented. I’d assume things used in the powders are anything from safe products to dangerous chemicals. BE CAREFUL ordering, using, and creating these products.