Yes, they can use the same dyes as you use for the rigid resins. The dye will go in the A-side of the Flex, stirred and suspended in the A-side before combining the A and B. It is best to dye the Flexible series on an as-needed/used basis. Something in the raw materials and the dyes will start to break down the Flex after they are mixed for an extended period of time and it will not perform as it does in its natural state. If you want to dye the resin for uniform coloring of pieces it is best to use it with in 5-7 days after dying. Make sure the A-side is shaken very well one hour prior to mixing, as the dyes and raw materials may start to separate over time. Always preheat your mold with the Flex series allowing a proper cure and the material to achieve full physical properties.