as for dimension precision, how to make your final decision when designing plastic structural, at first, as a professional designer, basic molding knowledge must be known, for instance, a larger gate size leads to a small shrinkage, parallel flow leads to a larger shrinkage. These factors will directly affect the dimension of the plastic parts, In mold structural side, the draft, the flash on the parting line and the abrasion of molding parts etc will also affect dimension precision.