The question may be what kinds of items go into each envelope?
Another bonus for keeping envelopes is I love sorting through any envelope because I will discover notes written to me so I would not forget flashes of ideas during the building of a wall hanging. Revisiting former designs provide me with reminders of possible titles I conjured up in the middle of cutting or stitching. Ideas are written on a scrap of paper or on the Master Pattern. There may also be an address or a quote I heard on the TV or radio. Who knows what I will find on any piece of documentation? Occasionally, it can be down right hilarious to see the notes I wrote to myself, which leads me to ask another question, What in the world were you thinking, Carol?
The clasp envelopes are my documentation of each work that I create. If I ever wish to piggyback from a former work and use an element in a different manner in a new work, I can open any envelope and find the starting point. I can read my notes of inspiration to cheer me forward to completion of an original idea with a different viewpoint. Or, I can be reminded of pitfalls I may have encountered along the way. Either discovery is highly useful.