Here's one I made earlier :)

Quick and dirty paint up guide for resin grenades ;

Resin grenade is primed and given a coat of white paint (after scrubbing with warm soapy water and a tooth brush). Using a thin strip of masking tape (1.5mm), the white stripe is masked off. The cap area is then airbrushed red.

Once dry the whole cap is masked off, and the body of the grenade is sprayed gloss black (Alclad black base - alternatively black gloss enamel). Once completely cured (at least 1 day) Alcad aluminium is airbrushed on (10-15 psi). Finished off using a metallic brass on the base (Gunze sangyo Mr Metallic Brass).