You can sew new jeans for a child from high-quality fabric, which, when performing all the necessary operations, will not be inferior in quality to store ones. For the same purpose, you can use sturdy, oversized jeans that are not worn by the wearer.
You will need a pattern of jeans for children that matches the height and size, but if it is not there, you can take any pants that fit your child well, including pajamas, as a sample. It will be difficult to do such work on hand and will take a very long time, so a sewing machine is also required for sewing. Use scissors, thread, needles, chalk or pencil, and an elastic band or string for a belt. Children's models do not fit very well and are uncomfortable when dressing, if they have buttons and zippers, the elastic band greatly simplifies this issue.
The remnants of fabric that formed when cutting out parts can be useful when decorating or, if necessary, put a patch, and it is better to save them.
The fabric is folded in half before being cut and pinned. This simplifies the cutting process, since all the details of the jeans are paired. The pattern is placed on the fabric and outlined with a pencil, leaving 2-3 cm seam allowances. It makes sense to leave a little more fabric at the bottom to dissolve it in the event of a sudden growth spurt in a child. The workpieces are cut, unfold and folded together with the front sides inward. All seams are made twice for greater strength, first grind the inner seams of the legs and the seam connecting both legs.
When the side seams are stitched, all cuts should be overlocked or zigzagged so that the fabric does not crumble during wear.
The jeans are turned inside out and a belt is sewn, which can be made from the same denim fabric, and also be knitted or from any other material. In the belt, inside empty, you need to leave a hole through which a cord or elastic will be inserted. Along the way, children's jeans can be decorated with bright buttons, buttons, rivets or appliqués. The bottom of the pants is sewn last, it is recommended to make this stitch in a zigzag so that it can be easily ripped open and lengthened. Well-tailored jeans will last for more than one year, and during this time a child's growth can greatly increase, but one cannot know about this in advance - all children grow and develop in different ways.
For sewing small size children's jeans, it is not necessary to purchase fabric. They can be successfully cut out of jeans of an adult size, provided that the fabric of those is not very worn out. To prepare for work, jeans should be washed well and then cut or ripped at all seams. The details are carefully smoothed out, deliberately unsuitable places can be immediately removed with scissors. If the pants have patch or welt pockets and other decorative elements, you can arrange the patterns in such a way that they become an adornment for children's jeans. If the pockets are torn or stained, it is better to remove them from the fabric. When pockets are ripped off, the denim underneath is usually much darker as it has less friction and less exposure to sunlight. Sometimes these abrupt color transitions on new pants are inappropriate, then you can sew new ones in place of old pockets or close these places with applique, embroidery, or a pattern.