this would be for gumpaste. Do you prefer gum tragacanth or tylose powder?
I use tylose in mine. My chef instructor used to use a formula that had gum tragacanth, but I think it's more expensive than the tylose.
Gum arabic isn't a substitute for gum tragacanth or tylose. You could substitute gum-tex, but it's not really a decent substitute for tylose.