If this thread is still going- gum arabic is used a lot in baking and sweet making so you could probably get it in baking stores or at your local chemist.
I also watched Kristina's post which was great but she used ready mixed gum. We get it in powder form (here in Cape Town) but I dont know what proportions to mix it to get the best results. I tried .5oz in 45 ml and it was very thick, but the print did work. I dont know how it will fire though- we will see!