comments:
Nairurian posted on r/mildlyinteresting2d
The only thing that matters is that you have directional freezing, ie. all sides except the top are insulated. This means that as the ice freezes, it’s ”pushing” the gasses (which is the main source of cloudiness in ice) towards the still liquid water. A mold like this is the same price as 32 of the ice cubes in the post and takes about as much effort as making normal ice (just a lot longer, ca 18-24h depending on your freezer).