Nelopah

Hello, my husband has taken up leatherworking and is starting to learn how to dye his works. I would like to make him some dyes from scratch and was wondering if anyone had in information they could share with me about this. Will tint's-all or Mixol (a tint for paints and stains), rit-dye, food colorant or any other easy to acquire pigments work? Thanks in advance for taking the time to respond! Carla