I use to keep few Kumantong during my youngest days. Here some of my knowing and hope it will help you.

Age around 8mth to 7 yrs old. I actually “invited” them from Thailand temple and some given to me by monks.

How they made?

Monks or those evil priests will dig out the grave of the babies and either using they bones or hairs (sometime powder from the tombstone) to curve into amulets (babies) forms. For those unborn (meaning die inside the mother wombs) to about the age of one the amulets figure will be like a baby climbing on the floor sucking pacifiers (very cute), those age about 2 to 8 yrs old, the figuring is a stand up or sitting baby figure and some age about 6 – 8 you can see them carry a weapons like arrow and bow.

The evil type (which mean they can’t rest in peace) the monk will blindfold them in red cloth, these sorts will take years to wash away they hater and sin by chanting daily. And never let then taste blood or it will be very difficult to tame them.

Feeding – There are a few way to feed Kumantong.
a) Sweet (Change once the sweet turn soft)
b) Chocolates (Same as above)
c) Fresh milk (which you need to change daily)
d) Plain rice (No much people use this)
e) Hard boil egg, peel off the shell (Change it once the egg turn black)
b) Blood of the owner, everyday per drop (Mainly use for those Kumantong dead of unnatural dead. Like adoption, kill by parent once born etc. Because of “hate” the become unrest soul and unlikely to be reborn again unless someone do offering of chatting by high monks to rest they soul. These are more “evil” type of feeding process, but also most effecting type, they will follow the owner heart, if the owner is “evil” the Kumantong will become like oneself, if the owner heart if “kind” the Kumantong will be good and wait for his/her change to be reborn.

How to keep?

a) You must treat them like your own kids, they got feeling too and you need to teach them what right what wrong.
b) If you have evil though, they will sense it and follow your mindset. They will help you to do evil deeds, but remembered this that you will have to pay back so how.
c) If you have kind though, they will also behave like you, but they will also help you in the way that you will live a smooth life. They will help you to clear any obstruction in your path.
d) They can be naughty sometime just like kids, so you as the daddy or mummy must punish them according same goes if they been a good boy you must awards them like buying new toys, clothing, sweet etc.

How do I get rid of them?

a) Is not easy of get rid of them like items you just throw down to the bin chute.
b) You cannot just throw them under a tree or far away, because they like dog, no matter how far you throw them, they will “stiff” they way back to you and disturb you.
c) If you really wanted to disposal them, you must bring them to a temple (For me I bring them back to Thai Temple at Simpang Bedok), together you must bring new clothing, plenty of sweets, toys etc and go to find the monk “on duty” that day and tell them that you don’t want to keep anymore. They will help you to chat and place them on the offering tables (Which many others Kumantongs “friends” sitting there), then you place your offering to all the others Kumantongs which been there before yours and tell them to take care of yours Kumantongs and “help” them not to bully them. Is a sort of bribing to them?

I get rid of mine because they are damn naughty and hard to tame, very playful. But they do help me in many ways like money and relationship which I rather not go into details