Chol HaMoed: No Expert Work

You may not do “expert” or “professional” work of certain types on chol ha'moed, and some types of expert craftsmen/women may not do their trades on chol ha'moed.
Examples
  • You may sew or lay bricks or other such labors, but not if you are an expert or professional in those fields and you are doing expert work.
  • Skilled writers and artists may not do their professional writing, calligraphy, or drawing (even for free!) on chol ha'moed. They may not do calligraphy or sofer work (Torah, tefilin, mezuza), but they may write normally.
  • If you are not a professional writer or expert craftsman/artist, you may write on chol ha'moed but the preferred practice is to use a shinu'i --an altered method of writing, such as:
    • Using your other hand,
    • Holding the pen/pencil differently from normal, or 
    • Writing diagonally across the paper.