Didn't read all the replies.....I have experience in mold making and casting bronze.
This company: www polytek.com....sorry couldn't get hot link to occur...anyway I have used them....they have all sorts of mold making conncoction,,,and a great catalog....they are in PA.
I would recomment making a rubber....silicon or cheaper polyuretheen mold from your original wax....
Silicon is so pliable.....it can do the odd shapes and undercuts....then you can make duplicates of the original and save what work you have done.
I do "ceramic shell" for the casting mold......this is a slurry of colodial silica in layers over the wax......
The ceramic shell is a bit more difficult....you will have to "sprue" and make "air vents" for the wax.....then make the ceramic shell.
then "burn out"......So you need a kiln and furnace....but aluminum melts much lower temp than aluminum....
You might consider checking out local colleges and universities....art schools....some of them have metal casting facilities.
Anyway, check out Polytek....they have a great catalog. That will get you started.
Idea....with the size of your item.....you can make a wax "tree" and cast several or more of them at the same time.
leland