Any liquid latex should do the trick, mould builder or something similar.
For latex peices you need to use acrylics, i base my pieces out in a pax paint base which is pros-aide and liquitex (or most acrylic brand) paint, i brush and sponge it on then airbrush fw acrylic inks over it, works well.
The other method is to mix latex and acrylic paint 50/50 and sponge that on then airbrush acrylics over that, some people airbrush the latex mix on, but i have not had much luck doing it that way, clogs the brush up to much, you can also try housepaint with latex not tried it myself but other people use it.