Some of the main limitations are regarding the minimum distance between walls, in order to
allow the material to flow freely to the more remote zones of the mould and the need to avoid acute internal angles less than approx 45°, where the thickness could decrease to an unacceptable degree. As with other moulding processes, it is better to follow all the usual rules regarding the size of radiuses, the requirement for draft, and stiffenings ribs. Moderate undercuts can be produced by slightly distorting the moulded part as it is removed from the mould.