For a small order, it is more curial to keep cost low so that the final price will not be too high to be accepted by the market. A simple design adjustment on plastic mold design and some sacrifice on the product color and plastic material will help the cost a lot.
If a product consists of a number of plastic parts, it will be costly to have individual plastic mold for each plastic part. The best way is to group different plastic parts by color and type of plastic required so that it is possible to group different plastic parts into the same plastic mold. As a result, it can reduce the number of plastic molds required and the product can enjoy the cost benefits from a multi-cavities molds.
In many cases, the color and type of plastic to be used for each plastic part hinder further grouping and still require a number of plastic molds to be built. Sacrificing color options and types of plastic are feasible and effective options so that the plastic parts can be grouped to fewer plastic molds.
It is true that the sacrifice will reduce the flexibility to make future changes and it usually conflicts what designer wants. However, it do help a lot in cost reduction in most of the cases. This allows more plastic parts can be placed into the same plastic mold and possible to enjoy significant cost reduce on plastic mold cost and product unit cost.
By combining different plastic parts into a plastic mold, the major drawback is that all involved plastic parts will be molded with the same color and same plastic material at a time. However, it is not saying that color matching is not possible and there is still a way to get around of this.
Color matching can still be achieved by molding different colors from different batches and manually do the color matching after the plastic molding. The by product from this is having excess plastic parts with the color that you may not want. Since it is a waste to discard the excess plastic parts, it is common for the remaining plastic parts to swop the colors in the other way or do a random color matching. A color matching planning before tool up the plastic mold is beneficial and this is a very good and feasible option for cost saving.
Standardization is another way to reduce the plastic mold cost and plastic molding cost. The standardization can be the same parts to be shared by the same product or by different product versions. This may reduce the number of plastic mold required or may allow a smaller plastic mold by taking out some identical plastic parts. If some plastic parts are nearly the same and vary on particular small portion, partial standardization is likely feasible. This is to make different metal inserts / blocks and share the same plastic mold. By changing the metal inserts, it allows the plastic mold to mold different plastic parts without raising a new plastic mold. A metal insert, of course, a lot less expensive than making a new plastic mold.
Designer usually does not care technical difficulty much and may design something pretty costly on plastic mold making and plastic molding. It is common that some design may require many side cores to overcome undercuts, which make the plastic mold complicated and slower to mold. Simplification on the design, shape or structure so as to minimize undercuts can save plastic mold cost and plastic molding cost significantly. This falls more on technical side and factory can give lots of advices.