I'm currently building my OpenROV and really struggled to find flowmix epoxy (In Italy). My workaround was to buy a suitable two-part epoxy and a pack of ten 5 ml syringes (the syringes were €1.59 for a pack of ten). You can then pour the two-part epoxy into a syringe, mix it with a toothpick, and then inject it as per a flowmix epoxy.
I hope this is useful to someone. I'm about to post something about pressure compensation (I'm trying to be helpful while my epoxy sets...) :-)