The diamond powder is very abrasive and is a hazard if inhaled. You should mix it in a small container with a closable lid. To make our own mixer we will start by bending a paperclip into a stirring paddle. the depth of the stirrer should be as deep as the container you have.
I found a small ear plug container in my assorted parts bin to use for this but a film canister would work well to, and in hind site I think a small ziplock bag and just squishing it would work real well also. Poke a hole in the lid for the stirrer and insert the bent paperclip .
Safety is king in the project. I thought it was funny i got this little branded reminder on my mixer.
Now we just add our ingredients. At a minimum I recommend using a good dust mask when adding the diamond powder. We are mixing 13 grams total of our compound, 5 diamonds, 4 grams Polydimethylsiloxane, 4 grams Polytetraflouroethylene.