You can easily make them at home (source, I did last weekend!).

- Dry ice (mine came from something shipped cold)

- Dark piece of metal (I used a 3D printer hot bed) on top of dry ice to get cold

- IPA vapour (I poured some on a shop towel)

- Some transparent container to house it all - I found a glass display cube on the side of the road, fish tanks or Tupperware also work.

- Torch or something to provide side lighting

Very cool to see evidence of the particles zooming around us, can highly recommend.