While checking the sugar syrup consistency if you find it difficult to check with hands as its hot. You can drop the sugar syrup in a bowl of water and check if it comes together and not dissolve in water.
If you dont want the sugar to crystallize add lemon juice once the one string consistency is reached.
You can either use rose syrup or Cardamom to flavor the sugar syrup.
Saffron can also be used.
The size of the boondis depends on the holes in the boondi ladle.