The word "nickelled" is not very common in current English usage, but there are some possible synonyms that could be used instead. One option might be "chrome plated," which refers to a similar process of adding a thin layer of metal to an object's surface. Other alternatives might include "silvered," "gilded," or "bronzed," depending on the specific type of metal or finish being applied. Regardless of which synonym is used, it is important to make sure that the word accurately reflects the process of coating or covering an object in a thin layer of metal, whether for decorative or functional purposes.