Well, I finally did a couple of batches of Essential beavers with bacon grease added.
My first batch was 1/2 tsp/1/2 cup plastic.
My second batch was 1 tsp/1/2 cup plastic.
With both batches, I reheated some plastic I'd already colored, salted, and used.
I added the bacon grease when I had the plastic up to pouring temps, stirred it in well, and injected it.
Both batches injected well, and filled the cavities.
The plastic, which was originally BJ med, did seem softer, but still felt strong.
I let them sit for a day, and then did a smell check. I could't smell the bacon grease.
I did not do a taste test. The grease has sat in a jar for a couple of months, so I was chicken. I seem to be a natural when it comes to giving myself food poisoning.
I have one of each batch rigged on a jig, and will test them next time out.
I'll report back.