You can add interest to your free form tatting by using multiple colors as in the blossoms pictured here, but you can also use multiple colors within each individual tatted ring or chain by using the maltese ring technique or by using needle tatting with two different colored threads wrapped alternately.
Two sizes of picot gauges are needed for this effect. Thread both tails through the eye of the tatting needle. Lay the first picot gauge on the needle and draw up the thread tight for the first double stitch.
Next make a double stitch using the second color thread and the second size of picot gauge. Alternate wrapping colors and gauges for length of chain or size of ring desired.
The two-color picots butterfly pictured above is a ring of 16 DS. The picots are between the second and third DS of each color and matching picots on the opposite side. The tails are knotted for antennae.
This technique can make unusual flowers from rings and chains.
For the two color bee pattern see: http://www.georgiaseitz.com/classes2001/essbee.html by Martha Ess.