My mother-in-law does a trunk show for local community groups all over the state (Wisconsin). She has a trunk & loads it with MANY things she has made over the years. She pulls them out at the presentation one at a time and explains what they are & how they are done. Sometimes she does a brief demo of the technique.
An example of a fabric swap would be if you were looking for a yard of fabric with bugs on it & I had it. I would give it to you in return for a yard of something you have that interests me. It can be done on an individual to individual basis or a group swap would be whoever on this forum (for instance) would like to just swap whatever for the fun of it. Could be a theme material or not.