The pieces will be sewn together using an overlocker, so only 5mm of seem allowance is necessary, exept in the ends of the legs and arms where 2 cm is better.
Sewing it together using the overlocker, it is important to remember not to sew across the pins, since the machine will be damaged. If the fabric has to be pinned, pin in the same direction as the edge's and 2 cm from it. Another good way to do it is to handstitch it first to be completely safe from damaging the machine.
When all pieces are sewn together the unitard is ready to be fabricated.