Bill
I round up my wood blank, just like you are going to make a spindle. I then cut a tennon and put it in my chuck. I install the cutter in a Jacobs chuck and drill the hole in the end of the wood. Keep the speed down as the tool tends to chatter and is hard to sand out. I have marked the cutter for the correct depth and that will depend upon who will be putting the thimble on their finger. I shape the outside and part off, allowing for enough wood to reshape the top. I made a tapered jam chuck for the thimble and turn and finish the top. Sand and finish with your favorite finish. I can knock one out in about 15 minutes. Best of luck making thimbles, they are a lot of fun.