how to solve overrmolding or double injection issues

To solve the problem of two-color mold,  before mold start manufacturing, the DFM analyse is most important.
Part material need design uniforml, choice an correct injeation gate position, good position for shut off the material between the diffrent color or material,  precision of mold manufacturing processing, then can get an very good product.
For these condition, it also need very experienced engineer and mold maker team.
Below picture is an 4-colour product.
First make an transparency PC lens, then put it into ABS material overmolding, then put it into acrylic material overmolding, then overmolding with TPE soft material.