I am actually nervous and propping the arm with fingers might be tricky, but my moto āIf others can do it - I can do it!ā.
I would need to buy a pool noodle - I think itās a neat trick @chatrat .
Iāve done a few Lauraās and was nervous about the fingers also, what I did was wrapped a hand towel around the wrist to hold it up higher in the box so the fingers were barely touching the polyfil. You pretty much have to adjust your methods with every sculpt but the main method stays the same. I used to wrap my limbs in saran wrap or rolled gauze but now do it how @chatrat does with an ace bandage which also prevents the vinyl from burning your hands.
I watched so many You Tube videos last night about heating Plastisol and making fish baits. Many re-heat their excess portions. I found only 1 related to reborns (in Spanish that I donāt understand) from the woman who explained the process. I only understand that she said to pour it in small portions.
The only one question that left from me is: since you said it set fast, can I hold the limb (at least when I am dealing with fingers and toes area) in my hands till it set? How long it would be? 10-15 -30 min?
I need to buy designated microwave also. Some people doing pouring in masks. Is it that toxic?
I was concerned about fumes after breast cancer so I put off my experiments.
Right, I was thinking of you when I saw that. 
When your pouring the thin layer in your cup cures quickly but once itās in the vinyl, it heats the vinyl retains the heat, so takes a lot longer to cure inside the limb then it would in an open container exposed to air. I personally wouldnāt want to hold it, its hot, takes roughly 45-60 minutes to soft set and would need to be kept in the same position.
And yes you definitely need a separate microwave and to wear a mask while heating and pouring. It had almost no odor once cured, but it has noxious fumes and very strong odor while itās heating and itās technically melted plastic, so I assume itās definitely not good for you to breathe.
That killed it for me! 
I am so sensitive to odors!
All my dreams are trashed! Going back to glass beads and poly-fill
Now I just need to buy a doll!
No donāt do it! It will scald your hand!
I have my microwave in my carport , so Iām heating and pouring outside, and thatās where everything stays until itās cured.
I picked up a cheap microwave off of Facebook marketplace. I use it on my back deck. I used a laser temperature gun and heated to the exact temperature they said so Iām not sure why mine had odor.
Thereās a few things it could be from the first would be the brand and type you used. The only brand I have found that had no odor after curing is bait plastics and only their low odor ultra clear line which ends in 42. I find the temp to be fickle, I used to use a thermometer when I first started but found that sometimes it would say it was to temp but there would still be tiny cloudy areas, the cloudy areas cause odor after curing. So itās best to heat for 30 seconds at a time and stop as soon as itās completely clear, which may be a slightly higher temp than recommended. If itās overheated too much it can also cause odor so checking every 30 seconds is crucial. The last could be improper mixing, the bottle needs to be turned upside and back for at least a full 60 seconds before pouring it into a container. While itās heating it needs to be stirred every 30-45 seconds. Those are the only things in all my experimenting that Iāve found make the difference between an odor or not.
I could still smell
It when my baby was put back together. Other than that I loved it.