Those machines to make yoghurts are an interesting example of how a glass serves for a lifetime. It's not the first time [...] that someone discards a perfectly durable material with theoretically unlimited uses after a single usage. With the machine, simply washing the glasses, it's easy to reuse them avoiding a very important quantity of waste if factors like average per year or person are taken into account.
There are options with low wattage (approx. 15W or less), keeping the right temperature for fermentation. They aren't particularly expensive and finally the user saves money at the same time.
You could make any kind of yoghurt from different types of milk, even mixing several ones both using milk powder or the own milk.
It also permits creativity when the user tries jam, cocoa, cream, fruits, vegetables, grainsor any particular idea, with the market as an aid for them. A market that, finally, is also the cause for a vast quantity of waste with the "single-use" dogma.
Here's a tip when the user wants a more creamy yoghurt: placing the yoghurt in horizontal, the milk serum tends to be separated, so you could release it from the glass. Doing a single time or perhaps several, the result is a more consistent yoghurt.