I temper my coloured cocoa butter in one batch (on marble) and then shave it to use little bits at a time.It is very fluid when warm so you need a decent amount of surface to work it.
If you use the pre-made colours, pop them in the microwave /bain marie for a while to melt PART of the mass, then shake vigorously. The unmelted portion together with the shaking will temper the rest, then you can squeeze out a tiny bit at a time to use. If your brushes cool, use a hair drier to warm them up again.

If you use an airbrush you don't need to temper the cocoa butter as the agitation from the process cools and tempers it on the way out of the brush. It's maybe not worth the hassle of cleaning for small quantities though, so I'd stick with a brush if that's the case.

The best colours to use for chocolate work are the fat soluable powders. I have only the 3 primary colour powders and mix my own colours from there on.
Making your own colours from the powder and cocoa butter is far more economical than buying the pre made stuff, (if you ever work for an employer who insist he won't buy you any "luxuries"...) but there is a bit more work involved:

Melt some cocoa butter, add in the colouring power and stir well, Allow to solidify, then melt again and stir well again. It's ready. With this you can tint your own white chocolate, or use it straight with paint brushes to paint or accent what ever you desire.

quote:

Is this is in powder or paste form? Who is chef rubber? what colours can you obtain? Are they expensive?

Also, I have great difficulty piping detail into the clear plastic novelty moulds. I can't see what Im doing as they are clear. Any suggestions would be gratefully received. Ive tried different coloured backgrounds but that doesn't really help.