Now that you have seen the basic method of working with set rhythms, you could apply the same thing to a study of triplets. Try using any of the rhythms from lesson 18. Also try triplets on any single beat or any combination of beats. Then add rests and finally, try any combination of triplets, eighth notes, quarter notes and rests. Here are some examples.
Here is a two bar set rhythm combining rests and triplet variations studied earlier.
Now apply the rhythm from the previous example to a full 12 bar progression.