Each mold is unique to the size of shells you plan on making... You're gonna need Plaster of Paris or some water cement for sure.
You need a ball the size that you want your shell to be which is just a little smaller in diameter than the mortar your firing from. So for a 3" shell you want a ball about 21/2" to allow for pasting and clearance room. Then you'll need a smaller ball to make the male half of the mold. The difference in these balls determins the thickness of your Hemi. So if the ball is 21/2" than the small ball should be about 23/8" unless you like really thick or thin Hemi's.
1. Plaster of Paris
2. large and small ball
3. 2 containers big enough for each ball to fit in.
4. a stick or dowel
How To:
Fill both containers about 1/2 to 3/4 full of Plaster of Paris. Now coat both balls in Vaseline (just realized how that sounds.... you know what I mean) stick them into the mold carefully exactly half way. Hlalf the ball should be sticking into the air and the other half in the Plaster of Paris. You should now see why you only fill the container partially....the Plaster will rise.
Let these set till they're dry. The vaseline should keep the balls from sticking....pull them out a little before it's completely dry to be safe (already hard but just not dry all the way through).
Now to make the male half, the former, just smear Vaseline all over the inside of the mold then pour some Plaster of Paris in the small mold and then push a stick or dowel for a handle into this wet cement about halfway. It will rise so try to get it to where the cement rises to the top. Don't push the handle to the bottom just halfway in. When it's hard enough to hold its shape pull it out and let it dry!!
Ther's your shell Mold!!
Cut some paper into squares. My mold holds 12 pieces but thats unique to the thickness of your mold and will therefore require some experimenting. Well smear these pieces of paper with glue and stack these pieces togethor. Obviously don't put glue on the bottom or it will glue ther, or the top of the stack or it will stick to the former. Put this stack on the mold and press down with the male half and the paper should form around the male half.
Leave this for the length of time the glue says it takes to dry. Then remove the male half and wait for the Hemi to finish drying. Just pop it out occasionally and feel if it's still wet.... When it's all dry cut the rough edges off and run it over some sandpaper to smooth the edges. To the left you see before and after trimming edges!!
