In public I make small quick things when I have attracted a crowd because I find the general public's average attention span including children is about 5 minutes. Where I can control all the space about me and the venue is close enough to my workshop for the sale of courses to be possible, then I allow suitable members of the public to 'have-a-go' but for my insurance to be operative I must supervise closely which means I can only do it when somebody is with me to 'mind the shop'. By making a nominal charge it is actually a very short private lesson and fully covered by my insurance. All appropriate safety equipment is provided for the client’s use and its use is mandatory.
These demonstrations make a very large impact on a show by bringing the craft to life, rather than a simple market stall, members of the public can come to appreciate fully what is involved in making the goods on display. In placing the pitch organisers should allow for an audience up to four persons deep, children naturally come to the front and if the aisles are not wide enough they can get squashed. I am used to managing the crowd to a degree in that I won't start up if it not safe to do so and I will abort if the aisles become blocked. When the crowd is poor I stave off boredom by just making stuff.
I have had problems with adjacent pitches where the craftworkers on either side of me are not used to working a crowd. The sort of stallholder who just sits and hopes tends to become sidelined and resentful.
The demonstrations contribute so much to the impact of the show on the general public that I will never pay for the additional demonstration space, in fact most of the promoters I work with don't charge for the side table either, they place me where I am a primary attraction, often in full view of the main entrance, to convince any doubters its worth coming in.
I clear up afterwards, a vacuum cleaner is part of my show kit!