How to make a crystal cave?

[lyrebird]

I have heard about this at school fairs, but have never seen it and don't know how to make one, and would REALLY like to do one for my son's birthday party this weekend (yes, not much time, I know). He's turning 6.

the idea is to have a tea chest (plywood box) and paint it dark blue with glitter and put smallish crystals in with plaster of Paris then the children (gnomes, dwarves, whatever) go crystal mining with head torches and hammer the crystals out.

Any ideas and/or practical suggestions?

Anyone know how long it would take for the plaster to set, how easy it will be to hammer the crystals out without breaking them, etc.?

thanks!

[lyrebird]

Here is how it all turned out:

Pied Piper story (soft ending, not Grimms) outside on a mattress in the garden then each child gets a musical instrument and we play follow the leader inside the house (did a couple of circuits, me playing my “pipe”) then outside onto obstacle course (bridge across the “river” and jumping over branches onto pile of cushions) then to the cave where the children were led (tent draped in cloths) and inside is a crystal cave (wooden box painted on inside with purple and glitter paint with crystals (tumbled stones) stuck on with clay). Then they all had a turn mining a crystal each (actually two each) and then washing the clay off in a bucket. Then loads of time to play and eat and have cake.

Worked a treat, only problem was the clay was starting to crack and a couple fell off the side of the box – not sure what the solution is. But plaster probably wouldn’t stick either. If I did it again I’d use quite wet clay and make sure it hasn’t dried too much before they go mining.

Higly recommended as an idea for 6 year old’s party, they loved it. (Phew!)

[LuxPerpetua]

This is a great idea.  Thanks for sharing how everything turned out!