What should I make and do for demonstrating medieval technology?

Any ideas? I have quite a lot of possibilities, involving various amounts of preparation and materials and explanation.

For starters, I could make Gold. Either mosaic gold, which may or may not require the use of mercury. Or I could tin plate lead. Or I could colour silver to make it look like gold, using either distilled eggs or a solution of sulphur and lime that apparently colours copper or silver yellow.

Then I could make some acid- nitric, HCl, Sulphuric. There is quite a list, but the problem is in demonstrating their uses, especially since I do not have any gold to experiment upon. I can mix them with some limestone, which would fizz satisfactorily.

I could distill eggs again. That would get me funny looks, but isn’t very entertaining except to hardened geeks. On the other hand small slow drips of yellow falling into a pot do catch peoples attention. It would be a good lead in to a discussion on the topic of early alchemy though.

Casting metals is also a good one, I have yet to see someone do that at an event. I intend to be the first. (At least in medieval circles that I am in)
There are so many things to be made, from thimbles up to spurs, or belt buckles, and large objects like a mortar and pestle, and candlesticks. I have not seen many people with medieval candlesticks, however they would be expensive in terms of material, and also time to make the mould and then cast the metal into it. (Also, you wouldn’t actually carry them around with you on campaign.) Nevertheless, they are what I aspire to do.
Simpler things can be made using pewter, also including belt studs, buckles, plates, tankards etc.
Of course, I would have to keep people a sensible distance away, at least 3 feet I think. As long as it is small amounts of metal I am dealing with, avoid moisture etc, there is little danger.

Faking coins. What I envisage is this:
I am sitting at my furnace, with a few silver coins of the period of the event. I also have a clay mould of said coins, which I show to the crowd. I then cut up one of the coins, put about 2/3 of it into a crucible with some copper or tin to make up the weight, then melt it, and cast it into the clay. By doing this several times I can end up with more silver than I started with, and more coins, thus netting more money. Once I crack the mould open, I pass the fake coin round, but my assistant will have nipped out the back to get some people pretending to be the local law officers. I will scarper out the back just before the law gets there, who will then arrest the MoP holding the fake coin, for counterfeiting, and lead them away, possibly explaining loudly to the crowd the punishments for counterfeiting.
I like it. Entertaining and educational, all in one go. I know who to get the coins from as well, I have plenty of copper and can get some silver.

I could also do some glassmaking of small things, like glass phials or beads. This would only be tricky insofar as the weather would have to be good and a lot of heat would be required. It would however be do-able, since it appears that the melting point of potash and sand based glass is around 1,000C, which my furnace can easily reach. There are also the health and safety aspects of trying to blow glass, especially in front of people.

On a more industrial scale, it would be easy to make quicklime. I would set up my furnace like a chimney, and pile in limestone and charcoal. It would however smell a lot, necessitating a large field, and a strong wind to take the pollution away. The same goes for ore smelting. I could roast copper ores to remove the sulphur, smelt iron ore using charcoal, ore and limestone. In fact the latter has already been done at Rivaulx abbey:
Iron ore smelting

It would be nice to repeat it. I do know one or two people with spare fields.

The tricky bits
Apart from all the fun stuff, the other problem is holding the crowd’s attention. Now, I don’t expect them to be 8 deep around me, but I have to be able to hold peoples attention whilst doing preparation for my experiments. This may mean I need an assistant to do some stuff and hand me some tools and equipment as I need them. I shall probably require a bellow monkey, to be paid either with beer or whatever else comes handy. Failing that I need a pyromaniac whose content to watch the flames all day and pump up the heat when necessary. I’m sure there are one or two of them around.

Several of my experiments or demos can be done at once. For example, I could start something distilling on top of the furnace, after having put on some metal to melt in the furnace, and when all that is going on, I can be moulding some clay, or grinding something up. This would keep me always busy doing something, so that the passing MoPs might see something they are interested in. The drawback is that MoPs are often very shy. If you are busy, many of them will not interrupt, except the annoying ones with stupid questions. So I need to have ways of opening it all up to them, so they can ask questions.

The other way of doing it is to have a lecture of some sort (obviously not the same kind as at school) where I show people things. For example, I can have half made clay moulds for showing people, as well as used ones, and the raw materials for making them. This would be easy enough to do, and keep them interested for the 5 or 10 minutes necessary before something else happens. The same thing can be done with some raw material, eg uncovering it and explaining how it is made. I could scrape the Spanish green off copper whilst something is distilling in the background, for example.

Another approach related to lecturing might be to set specific times when I will be doing something, such as casting a hand bell at 11am. This would enable people to gather to watch, and save me having to start and perhaps stop activity at odd times. All this would require is a friendly events organizer including me on the program, or a chalkboard somewhere obvious with timings on it. I would start with a general introduction, show of tools and materials, and get stuck in, hopefully with them asking questions as I work.

Each approach has its ups and downs, and to be honest, I shall be winging it at first. Writing specific plans shall be left until after I have some experience to back up my opinions. Outlines however are useful for jogging the memory, and I shall be writing them in my medieval notebook, using a quill pen. In fact this post is an outline, written to solicit comments on what I might be better off doing.