Someone else will have to chime in on all that (goals, etc), I can only guess (which I will). Seeing how open house is a PR driven event, then the underlying idea is to showcase and promote fired arts. I would think the primary goal is what activity can we do that does that. While cost should be kept in mind, the primary goal should not suffer because we are trying to save a few bucks.
Personally, I love the idea of committee members doing demos. It’s impressive for people to see, low cost and can really showcase the skills in the area. If the person working can also talk and answer questions about their work, the process and the spacess, even better. Project wise, I really like the air dry clay project idea. With the right clay it provides an experience that’s closer to fired ceramics without having to deal with the full firing process. If we go with Amico’s air dried Terra cotta and the right project, then there’s no need to paint. Folks can build something that day, using all the normal clay techniques they would with fired clay, and be able to take it with them.
But! Back the original topic. The student grade acrylic paints will be fine for the pendants. I’m unconcerned about coat thickness using those. On white bisque, it’ll take a single coat, 2 at the most for the lighter colors. If folks are getting fancy and layering colors, that changes things. The bisque does a great job of holding onto the paint too between partial absorption and providing some tooth, so you don’t need any type of primer coat.
With the craft paint because of variability in quality, but mostly because of low pigment ratios in the paint, I’ve had to use as many as 5 coats just to get semi solid coverage. With some colors I never could and had to work my way through several brands and various tints of reds/oranges/yellows until I found ones I was happy with. I’ve long since rekitted my acrylics setup so I have no idea what the exact paints I used were.