Step 1: Stuff You're Gonna Need...
2 Plastic baby doll arms & hands (try a craft store if you can't beg any off your sister)
Plaster of Paris
1-2 Tubes silicone caulk (any kind will work I like the clear 100% silicone stuff)
Gold and Silver KRYLON spray paint
A piece of scrap wood and a couple screws
Cooking spray (optional)
Small paintbrush (don't use your favorite sable brush, it's gonna get trashed)
Cup of soapy water
Tub and stick for mixing plaster
Step 2: Make a Mold of Those Precious Little Hands
First, make a stand like the picture below from the scrap wood and screws so that you have somewhere to put the hands while they are drying
We're going to cover the hands with the silicone caulk. It will take a few coats to get it thick enough (at leas 1/4") to be sturdy. You can use some cooking spray as a mold release. Spray it on the hands and then wipe it mostly off with a paper towel. I forgot to do this and the silicone still peeled right off so if you choose not to you'll probably be OK.
It's best to paint on the first coat with a brush to get all the detail. Squirt a dollop of silicone on a plate and start applying it with the brush. Work it into all the little crevices. After you get both hands coated cap the end of the caulk and go find something else to do. It's boring to watch caulk dry and it's going take a few hours at least.
Once the first coat is dry you can apply the silicone directly with the caulking gun. Have a cup of soapy water nearby. Once you have glopped on a bunch of silicone, dip your finger in the water and gently pat the caulk to work out the air bubbles and spread the silicone evenly.
It will probably take 3-4 coats to build it up to a 1/4" thickness. Make sure you goop generously around those chubby little fingers.
Once everything is dry take a sharp razor knife and carefully cut along both sides of the mold so that you can release the plastic baby doll hands. I left the area around the fingers intact and just wiggled them out. Gently remove the doll hands.
Step 3: Casting More, More, More
Put the molds in something to hold them upright. I used an old electrical junction box because it happened to be sitting nearby. Mix up some plaster to a pour-able consistency and fill the molds. Runny is good. It helps avoid trapped air bubbles. Jiggle the molds in the box for a minute to free any trapped air and then stick the hooks in when the plaster is stiff enough to hold them in place but before its too stiff to put them in at all. If you mess up and the plaster has already gotten too hard, no worries, just let it set, drill a hole in it later and glue a hook in. (ask me why I know this...)
Give the plaster 20-30 minutes to set and then un-tape the molds and carefully remove the gorgeous plaster hands you just cast. Now is a good time to do any smoothing of the seams if you want.
Repeat until you have a table full of plaster hands.
After you've made 40 million castings and you never want to see another baby hand, stop already and let them dry for a couple days. What? Don't want to wait a couple days? OK, you can dry them in the oven at the lowest setting for a couple hours.