I am doing it the old way they have been doing for 4000 years, there is a new way using molochite and sodium silicate to make the fire proof mold witch can be burnt out with a big LPG burner, its called ceramic shell casting, I have tried it but it was hard to get it to work.
If your making solid brackets you could use casting sand, I have dutch oil sand witch is very easy to use, or NZ green sand witch is a cunt to use but its cheep.
http://www.metcast.com/
They sell all the sands and refractory stuff, crucibles are cheep, around $30 for my 8 KG #A8, furnace has cast refractory cement witch is expensive or you could use Kawool, all my hand tools and burner etc I have made.