Being a Police Detective & a Jeweler for many years, I have made
such animals in the past.
For wax, I used a Ferris sticky wax. Roll it out into about a 1"
width and maybe 1/8 to 1/4 thickness. The thickness can be adjusted
Cut these into 1x1 squares on wax paper. I would then “flame
burnish” the top and allow to cool to room temperature.
Your “subject” preparation is also important. Fingerprinting
children can be a challenge, due to both attention span and their
skin development. Have the child wash their hands well with soap and
warm water. Then dry them well, finishing with a paper towel and
giving the fingers a good rub. What you are trying to do is make the
papillary ridges stand up on the fingers.
I would suggest that you use the thumb for the print as it is the
easiest digit to manipulate. How you press into the wax is hit and
miss, especially with kids. Try straight up / straight down with you
controlling the down pressure, NO Mooshing! A “heel to toe” motion
also works well.
After you get an acceptable print, carefully trim it to size
diameter but don’t putz with the thickness at this point. Sprue and
cast in whatever metal you want. Vacuum casting is a must as bubbles
will easily adhere to the print surface. After casting you can reduce
the thickness of the print by sanding, filing, etc. I found that
just leaving the surface of the print “frosted” from the pickle was
most attractive and showed of the ridges of the print. You can then
polish the edges and back.
Good luck! I’ve done a lot of tie tacks for cops over the years
using this technique.