I have some grand plans for a big elaborate kaleidoscope (which I’ll probably not get round to!) but thought I would have a play around with a smaller cardboard version at the weekend. The cheap plastic Petri dishes worked great as ‘cartridges’ to slot in different things to look at - salad-o-scope was a highlight
Might have to get started on the 3D printer to make some clips to hold the Petri dish in place for the next one.