The incorporation of hollow ribs, bosses and elevation changes in the design will allow much intricacy while still maintaining nominal thickness throughout. Avoiding thickness changes will eliminate uneven cooling which could cause shrinkage and warping. When thickness variation is unavoidable transitions should be gradual and uniform.

In general, where variations are necessary in a component, it should be fed from the heavier to the thinner section (see figure 2 below).
Large weight to surface ratios should definitely be avoided. In (see figure 3 below), the knob would have had an unacceptable shrinkage in the molding if molded from solid, as well as serious thermal cycle problems after plating.

Ribs are essential to reduce bulk or weight of components while retaining rigidity and strength. They should be designed so that they are 50 to 60 per cent of the wall thickness they are supporting at the point of intersection. This wall thickness ratio is important to avoid visible sink marks on the opposite side of the wall from the rib
(see figure 4 below).
Such shrinkage is made strikingly obvious after plating. Ribs should also be designed with proper radii at the intersection to avoid stress with a minimum draft of 1 degree to facilitate easy removal from the mould. The comments on wall thickness apply equally to bosses or studs on a molding for the attachment of related components.

Boss heights should not be more than twice the diameter. It is possible to design quite intricate systems of structurally interdependent bosses and ribs that provide dimensional rigidity and the attachment to related parts while maintaining wall thickness ratios and reducing both material needs and molding cycle times.

Unsupported edges may be be strengthened by turning the edge or 'setting' the linear plane of the wall (see figure 5 below).
Radius is of great importance at both internal and external intersections and should be as generous as possible to allow for a good flow of the molding material. For example, external radii should not be less than 1mm and internal radii not less than 0.5mm. Molded threads should be rounded rather than sharp and are not recommended under 6mm. Mechanical threading or tapping is not recommended for plastic parts that are to be electroplated. Recesses should be at least twice as wide as they are deep.

Finally, feed/gate areas need to be considerably larger than for normal ABS, and their position is important to avoid weld lines becoming visible. Other important parameters are material drying, tool temperatures and actual melt temperatures, together with injection speeds