The pigments sold for use in polyester/fiberglass construction are also suitable for use with epoxy. Though they are polyester-based, when used with epoxy they function as nonreactive diluents, which have no significant effect on the physical charactistics when used at recommended concentrations. As Bill said, a little goes a long way. 'Glass supply houses, TAP Plastics, and most marine dealers either have them or can get them for you. They are available in 2 oz. bottles for about $2, and can be mixed together with each other to create any color you desire. Some experimentation would be in order on scrap, though, because the color of cured epoxy is usually darker than the liquid form.

: Change of subject: Does anyone have experience with putting pigment in epoxy.
: I will be using MAS but am looking for red and yellow.