Hi Dieter only problem with using epoxy or Araldite is as Anthman pointed out, keeping balance. When using that particular brand (or any really) you need to keep revolving the "painted" item so that you don't get a "drip-lump" which will bugger the swimming action. Having said that though, I've used Araldite painted on with a disposable brush and the old "Superflex Secret Formula" epoxy also. You need to heat it with a hair dryer after mixing to get it really runny and 'disolve' bubbles. I only ever do it to seal paint where it's going to keep coming off and I have a rod lathe with 2 motors, 1 of which is a "dryer" that just revolves really slowly to prevent drip formation, it'd be a hassle otherwise as often when it's humid these coatings absorb moisture and take ages (sometimes 2-3 days to go "off") regardless of careful mixing and application. If you try it, do it on a nice dry hot day.
Have also tried Anti-graffiti coating to try and seal colour in some minnows I made up from lure blanks, but that was a big failure. Tried "Clear Floor" isocyanate free timber floor coating as well,(had some left after pulling up carpets and sanding/painting floor) which is thin and dries quickly, however didn't last long on plastic bodies. Other thing is that you need to be careful of is some of the paint/patterns on hard-body lures can get eaten by modern epoxies, so just a touch up with permanent metallic markers is often a better option, as is PaddyT's suggestion of using as is.
Regards Waza