Milk Carton Mandarin Agar 明治おいしい牛乳パック みかん寒天

I opened a carton of "Meiji Oishii Milk" to make mandarin orange milk agar. When you spread out the milk carton, the volume increases, and the liquid can be solidified without leaking out of the lid when it is re-tightened, so it was perfect for making agar.
Recipe
Ingredients:
1 pack of Meiji Oishii Gyunyu (450ml) (also used as a mold)
Large can of mandarin oranges (425 g)
60 g water
3 g agar agar powder
350g milk
60g sweetened condensed milk
45g sugar

How to make
1.Drain the syrup from a large can of mandarin oranges (425g) and remove the fruit.
2.Remove the entire contents of a 450ml carton of Meiji Oishii Milk.
3.Spread out the milk carton.
4.Put the mandarin oranges (220g) into the milk carton.
5.Make the agar solution. Put 60g of water and 3g of powdered agar into a pot and heat. Bring to a boil while stirring with a whisk. Once boiling, reduce the heat and cook for 2 minutes.
6.Turn off the heat for the moment. While stirring with a whisk, add 350g of milk and 60g of sweetened condensed milk. Add 45g of sugar and mix.
7.Put the mixture back on the heat. Heat until it comes to a boil, stirring constantly.
8.Strain through a sieve.
9.Pour the agar agar liquid into (4).
10.Cover with a lid. Once cooled, refrigerate to harden.
11.Done. Cut the bottom off the milk carton with scissors. When you open the lid, air will get in and it will be easier to get out.