We always take a bag of "things " with us to our Marlow Bottom Acoustic session ( shaky eggs, rattles,tambourines,etc) and lay them out on a table for people to pick up and join in with if a) they want to and b)it suits the tune ! I like to join in,if not playing,with different sized and filled glasses and two pens-----very satisfying !! But I guess not every session feels as comfortable with the arrangement as we do----although most of our joiners-in are pretty good,I have to say.