You can make a Will if you are over 18 years of age and have legal capacity. If you wish to make a Will and are under 18 years and have never been married, you can apply to the Supreme Court.
To have legal capacity to make a Will, you must know that you are making a Will, understand the nature and effect of the proposed Will and that you are distributing your property according to your own intentions.
If you are under 18 years and married, you can make a Will. Also, if you are under 18 years and are about to be married, you can make a Will in contemplation of that marriage. Your Will becomes valid when that marriage takes place.