This demonstration will require access to a small table and chair. Check with the event for this equipment.
The most difficult part of this demonstration will be keeping a pot of lead hot and doing so in a safe way where visitors and bystanders will not get hurt. Use a brazier if you can but keep it away from the visitors. If you cannot heat lead safely, pre-cast some samples and have some with and without a sprue. You can talk through the process with the mold. Also, have some sample sizes including a .75 ball to talk with, especially about the Brown Bess. DO NOT GIVE SAMPLE LEAD BALLS TO CHILDREN. The ball is both a choke hazard and toxic.
For cartridge rolling, do not use either real powder or lead balls. After making a cartridge, it can be given to a youngster in the crowd. Find a substitute for the ball (wood ball from hobby/craft shop or a paint ball and try to keep it led colored). Have precut papers, scissors and string. Use black aquarium sand or crush a charcoal briquette for your powder. Have a rolling stick. You might want a cartridge pouch handy to show how they were carried. Tradition has it that cartridges were given to the troops in “bricks” of twelve. Cartridge cases would typically have 23 holes, to store two bricks and one cartridge in their rifle. Some may also have 24 holes.