custom injection molding supplier

06:35 Jan 26, 2019 

As always, it would be more helpful to give a proper amount of context in the source language.

The translation problem here is that 'molding' is ambiguous, and risks a translation error.
A 'molding' can mean 'a part that is molded' — so this could be 'a supplier of custom molded parts'; the problem arises because in EN, when one noun is used to qualify another, it remains singular: so this becomes a 'custom molding[s] supplier' (no 's' for the plural) — this would be my instinctive native-speaker interpretation.

It is, however, possible (though I feel less likely) for it to mean 'a supplier of custom molding services', where a term like 'services' is implied but not stated.

Without more proper context, it is impossible to make an informed choice between these two possibilities, though my native-speaker instinct makes me prefer the former — in many marketing contexts, the copywriter will not miss the opportunity to add an extra 'buzzword' to their marketing message, like 'services' or 'solution', etc. Also, the use of the word 'supplier' points quite strongly to a physical object that is 'supplied', rather than say a 'service' that is 'provided'. All clues in the same direction.