When designing a part with threaded holes attempt to make other non-critical holes use the same size as the tap drill.

Target draft for injection molded products is 2 degrees. As little as 0.5 degree draft can be manufactured, however cost will be approximately 3x.  To get the advantages of a low draft surface use “low draft” ribs to minimize dragging during ejection.

Consider “Clinching” as opposed to Spot Welding, Riveting and Adhesives.  Clinching is a non-heat, non-pierce operation. Joints are watertight, dissimilar metals can be joined and clinching can be done on pre-painted parts.